Video encoding method and video decoding method

ABSTRACT

A video encoding method using a plurality of reference pictures includes: selecting whether or not a resilient picture referencing scheme is to be used for encoding video; writing a parameter indicating the selection into a header of an encoded video bitstream; and encoding a picture using inter-picture prediction using a result of the selection.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation application of PCT International Application No.PCT/JP2012/001013 filed on Feb. 16, 2012, designating the United Statesof America, which is based on and claims priority of U.S. ProvisionalPatent Application No. 61/443,373 filed on Feb. 16, 2011. The entiredisclosures of the above-identified applications, including thespecifications, drawings and claims are incorporated herein by referencein their entirety.

FIELD

One or more exemplary embodiments disclosed herein relate generally tomultimedia data coding, and relates in particular to a video encodingmethod and a video decoding method which utilize more than one referencepicture for inter-picture prediction.

BACKGROUND

A latest video encoding method, such as MPEG-4 AVC/H.264 (non patentliterature (NPL) 1) and a future generation high-efficiency video coding(HEVC), supports the inter-picture prediction utilizing motioncompensated prediction from more than one reference picture.

Recent advancements, such as ongoing development of an HEVC video codingstandard, may utilize a hierarchical coding structure in design,experiment, and evaluation activities. Advantages of the hierarchicalcoding structure include improved coding efficiency and improved picturequality. In the hierarchical coding structure, pictures are arranged intemporal levels where the lowest level represents a lowest frame rateand inclusion of subsequent high levels (the temporal level is 1 or 2)represents higher frame rates.

The temporal levels are also used for enabling a feature of temporalscalability of a coded video bitstream. Switching from a higher temporallevel (higher frame rate) to a lower temporal level (lower frame rate)is enabled by restricting picture referencing so that a current pictureonly refers to reference pictures at the same or lower temporal levels.On the other hand, switching from the lower temporal level to the highertemporal level is enabled by using a temporal nesting scheme. However,when a picture having a lower temporal level is decoded in a codingorder, reference pictures having higher temporal levels can no longer beused for prediction.

CITATION LIST Non Patent Literature

-   [NPL 1] ITU-T H.264 March 2010

SUMMARY Technical Problem

Switching from lower to higher temporal level can be performed at anytime by using a temporal nesting scheme according to a conventionaltechnique. However, such a scheme introduces some loss in codingefficiency due to its highly restrictive referencing structure.

Solution to Problem

One non-limiting and exemplary embodiment of the present disclosureprovides a new method for a resilient picture referencing scheme. Thenew method allows for more efficient inter-picture prediction withimproved error resilience, and provides switching points from lower tohigher frame rates in a temporally scalable coded video bitstream.

What is novel about the present disclosure is that a boundary picture isdefined for limiting picture referencing in the inter-pictureprediction, thereby allowing recovery in a decoding process whenmismatch occurs between an encoding process and the decoding process.Furthermore, a predetermined scheme for reference picture listconstruction using the present disclosure allows a hierarchical codingstructure to be performed which efficiently minimizes a bit of a signalfor performing reordering in the reference list. Lastly, the coded videobitstreams generated using the present disclosure inherently containstemporal scalability switching points.

In one general aspect, the techniques disclosed here feature a videoencoding method for encoding a current picture in a video using one ormore reference pictures, the video encoding method comprising: selectingwhether or not a temporally scalable scheme is to be used for encodingthe video; determining a classification of a picture in the video usinga result of the selection regarding the temporally scalable scheme;judging whether the picture is a key picture or not, the key picturehaving a predetermined temporal level; selecting, when theclassification of the current picture is determined as a predeterminedclassification indicating a picture usable as a switching point oftemporal levels, one or more valid reference pictures, each of which isthe key picture, out of all reference pictures in a reference picturememory, for the current picture; constructing a reference picture listincluding at least one of the one or more valid reference pictures; andencoding the current picture into a bitstream by performing motionprediction on the current picture using the one or more valid referencepictures in the reference picture list.

These general and specific aspects may be implemented using a system, amethod, an integrated circuit, a computer program, or acomputer-readable recording medium such as a CD-ROM, or any combinationof systems, methods, integrated circuits, computer programs, orcomputer-readable recording media.

Additional benefits and advantages of the disclosed embodiments will beapparent from the Specification and Drawings. The benefits and/oradvantages may be individually obtained by the various embodiments andfeatures of the Specification and Drawings, which need not all beprovided in order to obtain one or more of such benefits and/oradvantages.

Advantageous Effects

A video encoding method and a video decoding method according to one ormore exemplary embodiments or features disclosed herein provide a meansfor recovery of an error and for an optimal selection of a referencepicture in encoding and decoding video using a plurality of referencepictures. Accordingly, the effect of the present disclosure is in theform of improvement in error resilience and coding efficiency.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram which shows an example of error propagation whenmismatch occurs between an encoding process and a decoding process, andeffect according to the present disclosure which restricts the errorpropagation.

FIG. 2 is a diagram which shows an example of switching points fromlower to higher temporal levels in a coded video bitstream whichsupports temporal scalability.

FIG. 3 is a flowchart which shows a video encoding process using thepresent disclosure.

FIG. 4 is a flowchart which shows a video decoding process using thepresent disclosure.

FIG. 5 is a block diagram which shows an example of a video encodingapparatus using the present disclosure.

FIG. 6 is a block diagram which shows an example of a video decodingapparatus using the present disclosure.

FIG. 7 is a diagram which shows a location of a parameter indicatingwhether or not a resilient picture referencing scheme is used, in aheader of a coded video bitstream.

FIG. 8 is a flowchart which shows a video encoding process using a firstembodiment of a resilient picture referencing scheme according to thepresent disclosure.

FIG. 9 is a flowchart which shows the video encoding process using thefirst embodiment of the resilient picture referencing scheme accordingto the present disclosure.

FIG. 10 is a flowchart which shows a first embodiment of a process fordetermining a classification indicating whether a picture is a keypicture or not in the video encoding process using the resilient picturereferencing scheme according to the present disclosure.

FIG. 11 is a flowchart which shows a first embodiment of a process fordetermining a classification indicating whether a picture is a keypicture or not in the video decoding process using the resilient picturereferencing scheme according to the present disclosure.

FIG. 12 is a diagram which shows a location of a flag indicating aclassification on whether a coded picture is the key picture or not in aheader of a coded slice of the coded picture, according to the firstembodiment of the process for determining the classification indicatingwhether a picture is the key picture or not in the video encodingprocess and the video decoding process using the resilient picturereferencing scheme according to the present disclosure.

FIG. 13 is a flowchart which shows a second embodiment of the processfor determining the classification indicating whether a picture is thekey picture or not in the video encoding process using the resilientpicture referencing scheme according to the present disclosure.

FIG. 14 is a flowchart which shows a second embodiment of the processfor determining the classification indicating whether a picture is thekey picture or not in the video decoding process using the resilientpicture referencing scheme according to the present disclosure.

FIG. 15 is a diagram which shows a location of a parameter to specify atemporal level of a coded picture in a header of a coded slice of thecoded picture, according to the second embodiment of the process fordetermining the classification indicating whether a picture is the keypicture or not in the video encoding process and the video decodingprocess using the resilient picture referencing scheme according to thepresent disclosure.

FIG. 16 is a flowchart which shows a third embodiment of the process fordetermining the classification indicating whether a picture is the keypicture or not in the video encoding process using the resilient picturereferencing scheme according to the present disclosure.

FIG. 17 is a flowchart which shows the third embodiment of the processfor determining the classification indicating whether a picture is thekey picture or not in the video decoding process using the resilientpicture referencing scheme according to the present disclosure.

FIG. 18 is a diagram which shows a location of a parameter to specify aperiod of key pictures in a header of a coded video bitstream, accordingto the third embodiment of the process for determining theclassification indicating whether a picture is the key picture or not inthe video encoding process and the video decoding process using theresilient picture referencing scheme according to the presentdisclosure.

FIG. 19 is a block diagram which shows an example of a video encodingapparatus using the first embodiment of the resilient picturereferencing scheme according to the present disclosure.

FIG. 20 is a block diagram which shows an example of a video decodingapparatus using the first embodiment of the resilient picturereferencing scheme according to the present disclosure.

FIG. 21 is a flowchart which shows the video encoding process using asecond embodiment of the resilient picture referencing scheme accordingto the present disclosure.

FIG. 22 is a flowchart which shows the video decoding process using thesecond embodiment of the resilient picture referencing scheme accordingto the present disclosure.

FIG. 23 is a flowchart which shows a process for constructing areference picture list in the video encoding process and the videodecoding process using a second embodiment or a third embodiment of theresilient picture referencing scheme according to the presentdisclosure.

FIG. 24 is a flowchart which shows a first embodiment of a secondpredetermined scheme for performing sorting on the reference picturelist in the video encoding process and the video decoding process usingthe second embodiment or the third embodiment of the resilient picturereferencing scheme according to the present disclosure.

FIG. 25 is a flowchart which shows a second embodiment of the secondpredetermined scheme for performing the sorting on the reference picturelist in the video encoding process and the video decoding process usingthe second embodiment or the third embodiment of the resilient picturereferencing scheme according to the present disclosure.

FIG. 26 is a flowchart which shows a third embodiment of the secondpredetermined scheme for performing the sorting on the reference picturelist in the video encoding process and the video decoding process usingthe second embodiment or the third embodiment of the resilient picturereferencing scheme according to the present disclosure.

FIG. 27 is a block diagram which shows an example of the video encodingapparatus using the second embodiment of the resilient picturereferencing scheme according to the present disclosure.

FIG. 28 is a block diagram which shows an example of the video decodingapparatus using the second embodiment of the resilient picturereferencing scheme according to the present disclosure.

FIG. 29 is a flowchart which shows the video encoding process using thethird embodiment of the resilient picture referencing scheme accordingto the present disclosure.

FIG. 30 is a block diagram which shows an example of the video encodingapparatus using the third embodiment of the resilient picturereferencing scheme according to the present disclosure.

FIG. 31 is a diagram which shows a location of a parameter to specify areference list reordering step in a slice header of a coded videobitstream.

FIG. 32 is a diagram which shows an overall configuration of a contentproviding system for implementing content distribution services.

FIG. 33 is a diagram which shows an overall configuration of a digitalbroadcasting system.

FIG. 34 is a block diagram which shows a configuration example of atelevision.

FIG. 35 is a block diagram which shows a configuration example of aninformation reproducing/recording unit that reads and writes informationfrom and on a recording medium that is an optical disk.

FIG. 36 is a diagram which shows a configuration example of a recordingmedium that is an optical disk.

FIG. 37A is a diagram which shows an example of a cellular phone.

FIG. 37B is a block diagram which shows a configuration example of acellular phone.

FIG. 38 is a diagram which shows a structure of multiplexed data.

FIG. 39 is a diagram which schematically shows how each stream ismultiplexed in multiplexed data.

FIG. 40 is a diagram which shows how a video stream is stored in astream of PES packets in more detail.

FIG. 41 is a diagram which shows a structure of TS packets and sourcepackets in the multiplexed data.

FIG. 42 is a diagram which shows a data structure of a PMT.

FIG. 43 is a diagram which shows an internal structure of multiplexeddata information.

FIG. 44 is a diagram which shows an internal structure of streamattribute information.

FIG. 45 is a diagram which shows steps for identifying video data.

FIG. 46 is a block diagram which shows a configuration example of anintegrated circuit for implementing the moving picture coding method andthe moving picture decoding method according to each of embodiments.

FIG. 47 is a diagram which shows a configuration for switching betweendriving frequencies.

FIG. 48 is a diagram which shows steps for identifying video data andswitching between driving frequencies.

FIG. 49 is a diagram which shows an example of a look-up table in whichvideo data standards are associated with driving frequencies.

FIG. 50A is a diagram which shows an example of a configuration forsharing a module of a signal processing unit.

FIG. 50B is a diagram which shows another example of a configuration forsharing a module of the signal processing unit.

These and other advantages and features will become apparent from thefollowing description thereof taken in conjunction with the accompanyingDrawings, by way of non-limiting examples of embodiments disclosedherein.

DESCRIPTION OF EMBODIMENT(S) Underlying Knowledge Forming Basis of thePresent Disclosure

In relation to the conventional video coding method disclosed in theBackground section, the inventors have found the following problem.

A latest video coding scheme, such as MPEG-4 AVC/H.264 (NPL 1) and afuture generation high-efficiency video coding (HEVC), supportsinter-picture prediction utilizing motion compensated prediction frommore than one reference picture. In the case where there are more thanone reference pictures, one or more reference picture lists are createdfor the inter-picture prediction, and the reference pictures that aretemporally closer to a current picture are sorted to the top of thelists by a predetermined scheme. From the top to the bottom of thereference picture list, reference pictures are uniquely identified by areference index having an incremental value.

Recent advancements, such as ongoing development of an HEVC video codingstandard, utilize hierarchical coding structure in design, experiment,and evaluation activities. Advantages of the hierarchical codingstructure include improved coding efficiency and improved picturequality. In the hierarchical coding structure, pictures are arranged intemporal levels where the lowest level represents a lowest frame rateand inclusion of subsequent high levels (temporal level 1 or 2)represents higher frame rates. Examples of the hierarchical codingstructure are shown in FIG. 1 and FIG. 2. A certain amount of codinggain can be obtained by coding pictures at lower temporal levels withbetter quality (for example by applying less quantization) than picturesat higher temporal levels. In the HEVC, the temporal level is indicatedby means of a syntax parameter temporal_id located in a header of anetwork abstraction layer (NAL) unit of a coded slice of a picture.

The temporal level is also used for enabling the feature of temporalscalability of a coded video bitstream. Switching from a higher temporallevel (higher frame rate) to a lower temporal level (lower frame rate)is enabled by restricting picture referencing so that a current pictureonly refers to reference pictures at the same or lower temporal levels.On the other hand, switching from the lower temporal level to the highertemporal level is enabled by using a temporal nesting scheme. However,when a picture having the lower temporal level is decoded in a codingorder, reference pictures having higher temporal levels can no longer beused for prediction.

When mismatch between an encoding process and a decoding process exist,such as in the case of erroneous lossy transmission, the inter-pictureprediction may propagate the error across a large number of pictures, asillustrated in (a) of FIG. 1. In the (a) of FIG. 1, the error occurs ina picture B2 (the number 2 denotes the order of output). The picture B2is used as a reference picture for an inter-picture prediction processin a picture B3 and a picture B6, so that the error propagates to thepicture B3 and picture B6. Subsequent use of the picture B3 and thepicture B6 as reference pictures further propagates this error. Sucherror propagation is a major problem for a certain application such aslow delay video transmission over a public network.

Typically, different quality level is set for each picture correspondingto the temporal level as described above, to thereby improve subjectiveand objective result totally. The problem with the prior art is suchthat a reference picture which is temporally far-off and has low qualityis usually less useful than a reference picture which is temporallyfar-off and has high quality. Therefore, the reference picture which istemporally far-off and has low quality is included in the referencepicture list, resulting in sub-optimal coding efficiency, as a referenceindex corresponding to the reference picture which is temporally far-offand has high quality may require more signaling bits.

Using the temporal nesting scheme according to a conventional technique,switching from a lower temporal level to a higher temporal level can beperformed at any time. However, such a scheme introduces some loss incoding efficiency due to its highly restrictive referencing structure.

In view of the above, a video encoding method and a video decodingmethod according to one or more exemplary embodiments or featuresdisclosed herein provide a new method for a resistant picturereferencing scheme. The new method allows for more efficientinter-picture prediction with improved error resilience, and providesswitching points from a lower frame rate to a higher frame rate in atemporally scalable coded video bitstream.

Hereinafter, certain exemplary embodiments are described in detail withreference to the accompanying drawings. Each of the exemplaryembodiments described below shows a general or specific example. Thenumerical values, shapes, materials, structural elements, thearrangement and connection of the structural elements, steps, theprocessing order of the steps etc. shown in the following exemplaryembodiments are mere examples, and therefore do not limit the scope ofthe appended claims and their equivalents. The present disclosure isspecified by the scope of the claims. Therefore, among the structuralelements in the following exemplary embodiments, structural elements notrecited in any one of the independent claims are described as arbitrarystructural elements which are not indispensable for achieving thepresent disclosure but form more desirable embodiment.

According to an exemplary embodiment disclosed herein, a video encodingmethod for encoding a current picture in a video using one or morereference pictures, the video encoding method may include: selectingwhether or not a temporally scalable scheme is to be used for encodingthe video; determining a classification of a picture in the video usinga result of the selection regarding the temporally scalable scheme;judging whether the picture is a key picture or not, the key picturehaving a predetermined temporal level; selecting, when theclassification of the current picture is determined as a predeterminedclassification indicating a picture usable as a switching point oftemporal levels, one or more valid reference pictures, each of which isthe key picture, out of all reference pictures in a reference picturememory, for the current picture; constructing a reference picture listincluding at least one of the one or more valid reference pictures; andencoding the current picture into a bitstream by performing motionprediction on the current picture using the one or more valid referencepictures in the reference picture list.

For example, the video encoding method may further include writingclassification information indicating the classification of the currentpicture into a header of the bitstream.

For example, in the writing, a temporal level parameter indicating atemporal level of the current picture may be further written into theheader of the bitstream.

For example, in the judging, it may be judged whether or not a temporallevel parameter of the picture is zero; in the selecting of the one ormore valid reference picture, when the classification of the currentpicture having the temporal level parameter greater than zero isdetermined as the predetermined classification, one or more of the keypictures may be selected.

For example, in the writing, selection information and referenceinformation may be further written into the header of the bitstream, theselection information indicating the result of the selection regardingthe temporally scalable scheme, and the reference information indicatingthe reference pictures in the reference picture memory.

For example, the key picture may be an inter-predicted picture.

For example, in the selecting of the one or more valid referencepictures, when the classification of the current picture is notdetermined as the predetermined classification, a non-key picture may beselected as one of the one or more valid reference picture.

For example, in the selecting of the one or more valid pictures, whenthe classification of the current picture is not determined as thepredetermined classification, the all reference pictures in thereference picture memory may be selected as the one or more validreference pictures, the constructing may further include: constructing afirst reference picture list including one or more reference pictures inthe reference picture memory, using a temporal distance between each ofthe one or more reference pictures and the current picture; constructinga second reference picture list including the one or more validreference pictures, using the temporal distance between the each of theone or more reference pictures and the current picture and theclassification of the each of the one or more reference pictures;reordering the first reference picture list to make the first referencepicture list be equivalent to the second reference picture list; and inthe encoding, the current picture is predicted, using the reorderedfirst reference picture list.

For example, the video encoding method may further include: selecting afirst reference picture group including one or more key pictures out ofthe reference picture memory; identifying, when the classification ofthe current picture is not determined as the predeterminedclassification, (i) a first boundary picture as a key picture having anearest temporal instance to the current picture among key picturesdisplayed earlier than the current picture, and (ii) a second boundarypicture as a key picture having a nearest temporal instance to thecurrent picture among key pictures displayed later than the currentpicture; performing, when the second boundary picture is not present,(i) selection of a second reference picture group including anon-key-reference picture displayed later than the first boundarypicture, and (ii) addition of the second reference picture group to thefirst reference picture group; performing, when the second boundarypicture is present, (i) selection of a third reference picture groupincluding a non-key-reference picture displayed later than the firstboundary picture and earlier than the second boundary picture, and (ii)addition of the third reference picture group to the first referencepicture group; and placing the first reference picture group on thereference picture list which is sorted according to a predeterminedscheme, using the temporal distance to the current picture and theclassification.

A video encoding apparatus which encodes a current picture in a videousing one or more reference pictures, the video encoding apparatus mayinclude: a selection unit configured to select whether or not atemporally scalable scheme is to be used for encoding the video; aclassification determination unit configured to determine aclassification of a picture in the video using a result regarding theselection of the temporally scalable scheme; a judgment unit configuredto judge whether the picture is a key picture or not, the key picturehaving a predetermined temporal level; a valid reference pictureselection unit configured to select one or more valid referencepictures, each of which is the key picture, out of all referencepictures in a reference picture memory for the current picture, when theclassification of the current picture is determined as a predeterminedclassification indicating a picture usable as a switching point oftemporal levels; a reference picture list construction unit configuredto construct a reference picture list including at least one of the oneor more valid reference pictures; and an encoding unit configured toencode the current picture into a bitstream by performing motionprediction on the current picture using the one or more valid referencepictures in the reference picture list.

A video decoding method for decoding a bitstream corresponding to acurrent picture in a video using one or more reference pictures, thevideo decoding method may include: determining whether or not atemporally scalable scheme is to be used for decoding the video;obtaining a classification of a picture in the video, the classificationbeing determined by using a result of the determination regarding thetemporally scalable scheme; judging whether the picture is a key pictureor not, the key picture having a predetermined temporal level;selecting, when the classification of the current picture is apredetermined classification indicating a picture usable as a switchingpoint of temporal levels, one or more valid reference pictures, each ofwhich is the key picture, out of all reference pictures in a referencepicture memory, for the current picture; constructing a referencepicture list including at least one of the one or more valid referencepictures; and decoding the current picture by performing motionprediction on the current picture using the one or more valid referencepictures in the reference picture list.

For example, the video decoding method may further include obtainingclassification information indicating the classification of the currentpicture, from a header of the bitstream.

For example, the video decoding method may further include obtaining atemporal level parameter indicating a temporal level of the currentpicture, from the header of the bitstream.

For example, in the judging, it may be judged whether or not a temporallevel parameter of the picture is zero; in the selecting of the one ormore valid reference picture, when the classification of the currentpicture having the temporal level parameter greater than zero is thepredetermined classification, one or more of the key pictures may beselected.

For example, the video decoding method may further include obtainingselection information and reference information from a header of thebitstream, the selection information indicating whether or not thetemporally scalable scheme is to be used for decoding the video, and thereference information indicating the reference pictures in the referencepicture memory.

For example, the key picture may be an inter-predicted picture.

For example, in the selecting of the one or more valid referencepictures, when the classification of the current picture is not thepredetermined classification, a non-key picture may be selected as oneof the one or more valid reference picture.

For example, in the selecting of the one or more valid pictures, whenthe classification of the current picture is not the predeterminedclassification, the all reference pictures in the reference picturememory may be selected as the one or more valid reference pictures, theconstructing may further include: constructing a first reference picturelist including one or more reference pictures in the reference picturememory, using a temporal distance between each of the one or morereference pictures and the current picture; constructing a secondreference picture list including the one or more valid referencepicture, using the temporal distance between the each of the one or morereference pictures and the current picture and the classification of theeach of the one or more reference pictures; reordering the firstreference picture list to make the first reference picture list beequivalent to the second reference picture list; and in the decoding,the current picture is predicted, using the reordered first referencepicture list.

For example, the video decoding method may further include: selecting afirst reference picture group including one or more key pictures out ofthe reference picture memory; identifying, when the classification ofthe current picture is not the predetermined classification, (i) a firstboundary picture as a key picture having a nearest temporal instance tothe current picture among key pictures displayed earlier than thecurrent picture, and (ii) a second boundary picture as a key picturehaving a nearest temporal instance to the current picture among keypictures displayed later than the current picture; performing, when thesecond boundary picture is not present, (i) selection of a secondreference picture group including a non-key-reference picture displayedlater than the first boundary picture, and (ii) addition of the secondreference picture group to the first reference picture group;performing, when the second boundary picture is present, (i) selectionof a third reference picture group including a non-key-reference picturedisplayed later than the first boundary picture and earlier than thesecond boundary picture, and (ii) addition of the third referencepicture group to the first reference picture group; and placing thefirst reference picture group on the reference picture list which issorted according to a predetermined scheme, using a temporal distance tothe current picture and the classification.

A video decoding apparatus which decodes a bitstream corresponding to acurrent picture in a video using one or more reference pictures, thevideo decoding apparatus may include: a determination unit configured todetermine whether or not a temporally scalable scheme is to be used fordecoding the video; an obtainment unit configured to obtain aclassification of a picture in the video, the classification beingdetermined by using a result of the determination regarding thetemporally scalable scheme; a judgment unit configured to judge whetherthe picture is a key picture or not, the key picture having apredetermined temporal level; a valid reference picture selection unitconfigured to select one or more valid reference pictures, each of whichis the key picture, out of all reference pictures in a reference picturememory for the current picture, when the classification of the currentpicture is a predetermined classification indicating a picture usable asa switching point of temporal levels; a reference picture listconstruction unit configured to construct a reference picture listincluding at least one of the one or more valid reference pictures; anda decoding unit configured to decode the current picture by performingmotion prediction on the current picture using the one or more validreference pictures in the reference picture list.

For consistency of descriptions, this specification uses a conventionwhere primary pictures at the lowest frame rate with a lowest value ofthe temporal level (for example, the value 0) and subsequent highervalues of the temporal level (for example, the values 1, 2 and 3)indicate subsequent sets of pictures producing higher (double) framerates when added on a top of the lower temporal levels. The sameconvention is used in recent video coding schemes such as HEVC, H.264MVC extension and H.264 SVC extension, in which the temporal level isindicated using the syntax parameter temporal_id. It will be apparent tothose skilled in the art that an alternative convention where a greatervalue of the temporal level indicates a lower frame rate serves the samepurpose.

FIG. 1 shows an example of error propagation when mismatch occursbetween the encoding process and the decoding process such as due to thetransmission loss. In the prior art as shown in (a) of FIG. 1, the errormay propagate across a large number of pictures, often appearing aspersistent visual artifacts in a reconstructed picture. In the (a) ofFIG. 1, pictures affected by the error are indicated using hatchedshading. As shown in (b) of FIG. 1, in the present disclosure, keypictures are defined and picture referencing is restricted to shareborders with the nearest key pictures, so that the inter-pictureprediction from non-key pictures located temporally beyond the nearestkey pictures is not allowed. For simplicity, FIG. 1 shows a low delaycoding example where only forward prediction exists. However, therestriction of picture referencing to share borders with the nearest keypictures shall be applied in both forward and backward predictiondirections. Using the present disclosure, the error propagation isstopped at a key picture (picture B4) and subsequent pictures (picturesB5, B6, B7 and so on) can be perfectly reconstructed with no error.

FIG. 2 shows an example illustrating effects of the present disclosurein creating the switching point from lower to higher temporal levels inthe temporally scalable video bitstream. In the prior art, when thetemporal nesting is disabled as shown in (a) of FIG. 2, switching fromlower to higher temporal levels is not supported. For example, switchingto the highest frame rate (corresponding to a temporal level 2) cannotbe performed at the picture B5 because the picture B1 and the picture B3are necessary for the decoding of the picture B5.

When the temporal nesting is enabled in the prior art as shown in (b) ofFIG. 2, switching from lower to higher temporal levels can be performedat any point (as indicated in pictures by hatched shading). For example,switching to the temporal level 2 can be performed at the picture B5because the picture B5 is predicted from only a picture 10 and a pictureB4. However, when the temporal nesting is enabled, the picturereferencing becomes highly restrictive and tends to introduce loss incoding efficiency. On the other hand, in practical application of thetemporal scalable coding, the switching point may not be necessarilyprovided at every picture.

As described above, according to the present disclosure, the picturereferencing is restricted to share borders with the key pictures. As aresult, the first picture of each of the temporal levels, which followsthe key picture can be used as the switching point. For example, apicture B2 is a valid switching point to a temporal level 1, and thepicture B1 is a valid switching point to the temporal level 2.Subsequent pictures at an arbitrary temporal level (such as the pictureB3 at the temporal level 2) cannot be used as the switching point.However, the picture referencing for each of these subsequent picturesis less restrictive (for example, a picture B11 is allowed to use apicture B9 as prediction reference), so that more efficient coding isallowed. Therefore, the present disclosure provides some practicalbalance between temporal scalability property and coding efficiency.

FIG. 3 is a flowchart which shows the video encoding process using thepresent disclosure. It should be noted that a module described in thespecification of the present application is a software module or ahardware module. A module 300 selects whether a resilient picturereferencing scheme is used or not. A module 302 then writes a parameterinto a header of a coded video bitstream indicating the selection. Next,a module 304 performs encoding on a picture using the inter-pictureprediction using the result of the selection. When the resilient picturereferencing scheme is used, a reference picture selection process and anordering process are performed in a manner that the picture referencingis restricted to share the boundary with the key pictures, as describedabove. In this specification, the following shall describe, in detail,embodiments of the resilient picture referencing scheme.

FIG. 4 is a flowchart which shows a video decoding process using thepresent disclosure. A module 400 parses a parameter indicating whetherthe resilient picture referencing scheme is used or not, from the headerof the coded video bitstream. Next, a module 402 judges whether theresilient picture referencing scheme is used or not.

When the resilient picture referencing scheme is used, a module 404performs partial decoding on the coded video bitstream using theresilient picture referencing scheme. In the partial decoding, theresilient picture referencing scheme is used in the same way as theencoding process. In the partial decoding, the decoding process on somecoded pictures is omitted without influencing the decoding process onother coded pictures.

When the resilient picture referencing scheme is not used, a module 406performs a full decoding on a coded video bitstream without using theresilient picture referencing scheme.

FIG. 5 is a block diagram which shows an example of a video encodingapparatus using the present disclosure. The video encoding apparatusincludes a referencing scheme selection unit 500, an encoding unit 502,a writing unit 504, and a memory unit 506.

As shown in FIG. 5, the referencing scheme selection unit 500 selectswhether the resilient picture referencing scheme is used or not. Theencoding unit 502 uses a scheme selection D501 which is a selectionresult by the referencing scheme selection unit 500 and a referencepicture D511 stored in the memory unit 506, to encode an uncompressedoriginal image D503 using the inter-picture prediction. As a result,coded picture data D505 and reference picture data D507 are obtained.The writing unit 504 then takes the coded picture data D505 and thescheme selection D501 to produce a coded video bitstream D509. Thereference picture data D507 which includes a reconstructed sample of theoriginal image D503 is stored into the memory unit 506. In one possibleimplementation of the present disclosure using the first embodiment ofthe resilient picture referencing scheme, the reference picture dataD507 further includes a picture marking signal for marking the referencepicture stored in the memory unit 506 as used for reference or as unusedfor reference.

FIG. 6 is a block diagram illustrating an example of a video decodingapparatus using the present disclosure. The video decoding apparatusincludes a parsing unit 600, a first switch unit 602, a first decodingunit 604, a second decoding unit 606, a second switch unit 608, and amemory unit 610.

As shown in FIG. 6, the parsing unit 600 parses a header of a codedvideo bitstream D601 to obtain a parameter D603 indicating a selectionwhether the resilient picture referencing scheme is used or not. Basedon the parsed parameter D603, the switch unit 602 sends the coded videobitstream D601 either to the first decoding unit D604 or to the seconddecoding unit D606.

When a reference picture D615 stored in the memory unit 610 is used, thefirst decoding unit D604 performs partial decoding on the coded videobitstream D605 using the resilient picture referencing scheme. In thepartial decoding, the decoding processes of some coded pictures areomitted without influencing the decoding process of other codedpictures. In one possible implementation of the present disclosure usingthe first embodiment of the resilient picture referencing scheme, thefirst decoding unit D604 sends a picture marking signal D616 for markingreference pictures stored in the memory unit 610 as used for referenceor as unused for reference.

On the other hand, using the reference picture D615 stored in the memoryunit 610, the second decoding unit D606 performs full decoding of acoded video bitstream D609 without using the resilient picturereferencing scheme. Based on the parsed parameter D603, the secondswitch unit 608 switches a reconstructed picture to be sent, as theoutput D613 of the decoding process, between a reconstructed pictureD607 from the first decoding unit D604 and a reconstructed picture D611from the second decoding unit 606. The reconstructed picture serving asthe output D613 of the decoding process is also stored into the memoryunit 610 to be used in an inter-picture predicted decoding process ofsubsequent coded pictures.

FIG. 7 is a diagram which shows a location of a parameter indicatingwhether the resilient picture referencing scheme is used or not, in aheader of a coded video bitstream. Examples of the parameter include aflag with a value 1 indicating that the resilient picture referencingscheme is used and a value 0 indicating that the resilient picturereferencing scheme is not used. A drawing (a) of FIG. 7 shows a locationof the parameter in a sequence header of a compressed video bitstream. Adrawing (b) of FIG. 7 shows a location of the parameter in a pictureheader of the compressed video bitstream. A drawing (c) of FIG. 7 showsa location of the parameter in a slice header of the compressed videobitstream. A drawing (d) of FIG. 7 shows that the parameter can also bederived from a predetermined look-up table based on a profile parameter,a level parameter, or both profile and level parameters which arelocated in a sequence header of the compressed video bitstream.

FIG. 8 is a flowchart showing a video encoding process using the firstembodiment of the resilient picture referencing scheme according to thepresent disclosure. A module 800 determines a classification indicatingwhether a picture is a key picture or not. The following shall describe,in detail, embodiments of the classification indicating whether apicture is a key picture or not. A module 802 judges whether a currentpicture is a key picture or not. When the current picture is the keypicture, a module 804 marks a non-key reference picture stored in apicture memory as unused for reference.

Next, regardless of whether the current picture is the key picture ornot, a motion estimation process is performed on a block of an imagesample using the reference picture marked as used for reference in themodule 804, and a motion prediction process is performed on the block ofthe image sample using the reference picture marked as used forreference in a module 808.

FIG. 9 is a flowchart which shows a video decoding process using thefirst embodiment of the resilient picture referencing scheme accordingto the present disclosure. A module 900 determines a classificationindicating whether a picture is the key picture or not. Then, a module902 judges whether the current picture is the key picture or not. Whenthe current picture is the key picture, a module 904 marks the non-keyreference picture stored in the picture memory, as unused for reference.

Next, regardless of whether the current picture is the key picture ornot, the motion prediction process is performed on the block of theimage sample using the reference picture (other than the referencepicture marked as unused for reference) marked as used for reference inthe module 906.

FIG. 10 is a flowchart which shows the first embodiment of the processfor determining a classification indicating whether a picture is a keypicture or not in the video encoding process using the resilient picturereferencing scheme according to the present disclosure. In a module1000, a flag indicating a classification on whether the coded picture isthe key picture or not is written into a header of a coded slice of acoded picture.

FIG. 11 is a flowchart which shows the first embodiment of the processfor determining a classification indicating whether a picture is a keypicture or not in a video decoding process using the resilient picturereferencing scheme according to the present disclosure. In a module1100, a flag indicating the classification on whether the coded pictureis the key picture or not is parsed from a header of a coded slice of acoded picture.

FIG. 12 is a diagram which shows a location of a flag indicating aclassification on whether a coded picture is the key picture or not, ina header of a coded slice of a coded picture, according to the firstembodiment of the process for determining the classification indicatingwhether a picture is the key picture or not in the video encodingprocess and the video decoding process using the resilient picturereferencing scheme according to the present disclosure. In a coded videobitstream, a coded picture is represented in one or more slice networkabstraction layer units (NALU). The flag indicating the classificationof pictures is located in the NALU header of the slice NALU.

FIG. 13 is a flowchart which shows a second embodiment of the processfor determining the classification indicating whether a picture is thekey picture or not in the video encoding process using the resilientpicture referencing scheme according to the present disclosure. First, amodule 1300 writes a parameter into a header of a coded slice of a codedpicture to specify a temporal level of the coded picture. Examples ofthe parameter to specify the temporal level include the syntax parametertemporal_id in the HEVC video coding scheme. Then, a module 1302 judgeswhether the parameter has a value equal to a predetermined value.Examples of the predetermined value include the value 0 indicating thelowest temporal level corresponding to the lowest frame raterepresentation. When the parameter value is equal to the predeterminedvalue, a module 1304 classifies the coded picture as the key picture.When the parameter value is not equal to the predetermined value, amodule 1306 classifies the coded picture as a non-key picture.

FIG. 14 is a flowchart which shows the second embodiment of the processfor determining the classification indicating whether a picture is thekey picture or not in the video decoding process using the resilientpicture referencing scheme according to the present disclosure. First, amodule 1400 parses a parameter from a header of a coded slice of a codedpicture to specify the temporal level of the coded picture. Then, amodule 1402 judges whether the parameter has a value equal to apredetermined value. When the parameter value is equal to thepredetermined value, a module 1404 classifies the coded picture as thekey picture. When the parameter value is not equal to the predeterminedvalue, a module 1406 classifies the coded picture as the non-keypicture.

FIG. 15 is a diagram which shows a location of the parameter to specifythe temporal level of the coded picture in a header of a coded slice ofa coded picture, according to the second embodiment of the process fordetermining the classification indicating whether a picture is the keypicture or not in the video encoding process and the video decodingprocess using the resilient picture referencing scheme according to thepresent disclosure. A drawing (a) of FIG. 15 shows a location of theparameter representing a coded picture in a NALU header of a slice NALU.A drawing (b) of FIG. 15 shows the location of the parameter in a sliceheader of a compressed video bitstream.

FIG. 16 is a flowchart which shows a third embodiment of the process fordetermining the classification indicating whether a picture is the keypicture or not in the video encoding process using the resilient picturereferencing scheme according to the present disclosure. First, a module1600 writes a parameter into a header of a coded video bitstream tospecify a period of key picture. Then, a module 1602 judges whetherpicture number of pictures (in an output order) is equal to an integermultiple of the period of key pictures. When the picture number ofpictures is equal to an integer multiple of the period of key pictures,a module 1604 classifies the picture as the key picture. When thepicture number of the picture is not equal to an integer multiple of theperiod of key pictures, a module 1606 classifies the picture as thenon-key picture. Examples of the parameter value specifying the periodof key pictures include the value 4 which indicates that each of the keypictures occur every 4 pictures. In this case, pictures having picturenumbers 0, 4, 8, 12 and so on according to the output order areclassified as the key picture, whereas all other pictures are classifiedas the non-key picture.

FIG. 17 is a flowchart which shows a third embodiment of the process fordetermining the classification indicating whether a picture is the keypicture or not in the video decoding process using the resilient picturereferencing scheme according to the present disclosure. First, a module1700 parses a parameter from a header of a coded video bitstream tospecify the period of key pictures. Then, a module 1702 judges whetherthe picture number of coded pictures (in the output order) is equal toan integer multiple of the period of key pictures. When the picturenumber of the coded picture is equal to the integer multiple of theperiod of key pictures, a module 1704 classifies the coded picture asthe key picture. When the picture number of the coded picture is notequal to the integer multiple of the period of key pictures, a module1706 classifies the coded picture as the non-key picture.

FIG. 18 is a diagram which shows the location of the parameter tospecify the period of key pictures in a header of a coded videobitstream, according to the third embodiment of the process fordetermining the classification indicating whether a picture is the keypicture or not in the video encoding process and the video decodingprocess using the resilient picture referencing scheme according to thepresent disclosure. A drawing (a) of FIG. 18 shows a location of theparameter in a sequence header of a compressed video bitstream. Adrawing (b) of FIG. 18 shows a location of the parameter in a pictureheader of the compressed video bitstream. A drawing (c) of FIG. 18 showsa location of the parameter in a slice header of the compressed videobitstream. A drawing (d) of FIG. 18 shows that the parameter can also bederived from a predetermined look-up table based on a profile parameter,a level parameter, or both profile and level parameters which arelocated in the sequence header of the compressed video bitstream.

FIG. 19 is a block diagram illustrating an example of a video encodingapparatus using the first embodiment of the resilient picturereferencing scheme according to the present disclosure. The videoencoding apparatus includes a classification determining unit 1900, amemory unit 1902, a first switch unit 1904, a marking unit 1906, asecond switch unit 1908, a list creation unit 1910, a motion estimationunit 1912, a motion prediction unit 1914, and a writing unit 1916.

As shown in FIG. 19, the motion estimation unit 1912 reads a block D1919of an image sample, one or more reference picture lists D1917, andoutputs a motion vector set D1921. The motion prediction unit 1914 readsthe motion vector set D1921 and the reference picture list D1917 ofreference pictures, and outputs a predicted sample block D1923.

The classification determining unit 1900 reads input data D1901 andperforms processing thereon to produce a classification signal D1903indicating whether a picture is the key picture or not and output dataD1925. The output data D1925 is written by the writing unit 1916 into acoded video bitstream D1927.

In one possible implementation of the present disclosure using the firstembodiment of the process for determining the classification indicatingwhether a picture is the key picture or not in the video decodingprocess as described referring to FIG. 10, the input data D1901 is aflag indicating a classification on whether the coded picture is the keypicture or not. According to this embodiment, the classificationdetermining unit 1900 simply passes the flag as both its outputs, i.e.,the classification signal D1903 and the output data D1925.

In another possible implementation of the present disclosure using thesecond embodiment of the process for determining the classificationindicating whether a picture is the key picture or not in the videodecoding process as described referring to FIG. 13, the input data D1901is the temporal level of a coded picture. Using the temporal level ofthe coded picture, the classification determining unit 1900 determinesand outputs the classification signal D1903 indicating whether a pictureis the key picture or not. According to this embodiment, theclassification determining unit 1900 also sends, as the output dataD1925, the temporal level of the coded picture to the writing unit 1916.

In yet another possible implementation of the present disclosure usingthe third embodiment of the process for determining the classificationindicating whether a picture is the key picture or not in the videodecoding process as described in FIG. 16, the input data D1901 may bethe period of key pictures. Using the period of key pictures, theclassification determining unit 1900 determines and outputs theclassification signal D1903 indicating whether a picture is the keypicture or not. According to this embodiment, the classificationdetermining unit 1900 also sends, as the output data D1925, the periodof key pictures to the writing unit 1916.

The first switch unit 1904 uses the classification signal D1903 as acontrol signal for switching destination of the reference pictures D1905from the memory unit 1902, between the second switch unit 1908 when aclassification signal D1903 indicates the non-key picture and themarking unit 1906 when the classification signal D1903 indicates the keypicture. The marking unit 1906 checks the input reference picturesD1909, then sends a marking signal D1911 to mark a non-key-referencepicture in the memory unit 1902 as unused for reference, and to output areference picture marked as used for the reference picture D1913. Thesecond switch unit 1908 switches selection between the reference pictureD1907 and the reference picture D1913 based on the classification signalD1903. The list creation unit 1910 reads the reference picture D1915 andoutputs one or more reference picture lists D1917.

FIG. 20 is a block diagram which shows an example of a video decodingapparatus using the first embodiment of the resilient picturereferencing scheme according to the present disclosure. The videodecoding apparatus includes a classification determining unit 2000, amemory unit 2002, a first switch unit 2004, a marking unit 2006, asecond switch unit 2008, a list creation unit 2010, and a motionprediction unit 2012.

As shown in FIG. 20, the motion prediction unit 2012 reads a decodedmotion vector set D2019, one or more reference picture lists D2017, andoutputs a predicted sample block D202.

The classification determining unit 2000 reads the input data D2001 andperforms processing thereon to produce a classification signal D2003indicating whether a picture is the key picture or not.

In one possible implementation of the present disclosure using the firstembodiment of the process for determining the classification indicatingwhether a picture is the key picture or not in the video decodingprocess as described referring to FIG. 11, the parsed input data D2001is a parsed flag indicating a classification on whether the codedpicture is the key picture or not. According to this embodiment, theclassification determining unit 2000 simply output the parsed flag asthe classification signal D2003.

In another possible implementation of the present disclosure using thesecond embodiment of the process for determining the classificationindicating whether a picture is the key picture or not in the videodecoding process as described referring to FIG. 14, the parsed inputdata D2001 is the temporal level of the coded picture. Using thetemporal level of the coded picture, the classification determining unit2000 determines and outputs the classification signal D2003 indicatingwhether a picture is the key picture or not.

In yet another possible implementation of the present disclosure usingthe third embodiment of the process for determining the classificationindicating whether a picture is the key picture or not as describedreferring to FIG. 17, the parsed input data D2001 is a parsed period ofkey pictures. Using the parsed period of key pictures, theclassification determining unit 2000 determines and outputs theclassification signal D2003 indicating whether a picture is the keypicture or not.

The first switch unit 2004 uses the classification signal D2003 as acontrol signal for switching the destination of a reference pictureD2005 from the memory unit 2002, between the second switch unit 2008when the classification signal D2003 indicates the non-key picture, andthe marking unit 2006 when the classification signal D2003 indicates thekey picture. The marking unit 2006 checks the input reference picturesD2009, then sends a marking signal D2011 to mark the non-key referencepicture in the picture memory 2002 as unused for reference and outputs areference picture D2013 marked as used for reference. The second switchunit 2008 switches selection between the reference picture D2007 and thereference picture D2013 based on the classification signal D2003. Thelist creation unit 2010 reads the reference picture D2015 and outputsone or more reference picture lists D2017.

FIG. 21 is a flowchart which shows a video encoding process using thesecond embodiment of the resilient picture referencing scheme accordingto the present disclosure. A module 2100 determines a classificationindicating whether a picture is the key picture or not. Detailedembodiments of the step for determining the classification indicatingwhether a picture is the key picture or not are given in earlierdescriptions in this specification. A module 2102 then constructs areference picture list using a temporal distance to the current pictureand the classification indicating whether a picture is the key pictureor not. Next, the motion estimation process is performed on the block ofthe image sample using the reference picture list in a module 2104, anda motion prediction process is performed on the block of the imagesample using the reference picture list in module 2106.

FIG. 22 is a flowchart which shows a video decoding process using thesecond embodiment of the resilient picture referencing scheme accordingto the present disclosure. A module 2200 determines a classificationindicating whether a picture is the key picture or not. A module 2202then constructs a reference picture list using the temporal distance tothe current picture and the classification indicating whether a pictureis the key picture or not. Next, a motion prediction process isperformed on the block of the image sample using the list of thereference pictures in a module 2204.

FIG. 23 is a flowchart which shows the process for constructing areference picture list in the video encoding process and the videodecoding process using the second or third embodiment of the resilientpicture referencing scheme according to the present disclosure. As shownin FIG. 23, a module 2300 selects a first reference picture groupincluding a key picture. A module 2302 then creates a reference picturelist including the first reference picture group sorted by a firstpredetermined scheme using the temporal distance to the current picture.Next, a module 2304 judges whether the current picture is the keypicture or not.

When the current picture is the key picture, the reference listconstruction process is completed. Otherwise, when the current pictureis not the key picture, a module 2306 identifies a first key boundarypicture as a key reference picture having a temporal instance earlierthan and nearest to the current picture. Next, a module 2308 judgeswhether a second boundary picture is present or not, whereas the secondboundary picture is identified as the key reference picture having atemporal instance later than and nearest to the current picture.

When the second boundary picture is not present according to thejudgment by module 2308, a module 2314 selects a second referencepicture group including a non-key-reference picture having a temporalinstance later than the first boundary picture, and a module 2316 addsthe second reference picture group into the reference picture list.

When the second boundary picture is present according to judgment by themodule 2308, a module 2310 selects a third reference picture groupincluding the non-key-reference picture having a temporal instance laterthan the first boundary picture and earlier than the second boundarypicture, and a module 2312 adds the third reference picture group intothe reference picture list.

Next, regardless of whether the second boundary picture is present ornot, the resulting reference picture list (after adding either second orthird reference picture group) is stored by a module 2138 using a secondpredetermined scheme using the temporal distance to the current pictureand the classification indicating whether a picture is the key pictureor not.

FIG. 24 is a flowchart which shows the first embodiment of the secondpredetermined scheme for a process of performing sorting on thereference picture list in the video encoding process and the videodecoding process using the second or third embodiment of the resilientpicture referencing scheme according to the present disclosure. First, amodule 2400 places the key reference picture at the top of the referencepicture list according to the temporal distance to the current picture.Then, a module 2402 places the non-key reference picture in the listafter the key reference picture according to the temporal distance tothe current picture. In one possible implementation of the secondpredetermined sorting scheme, the steps of placing reference pictures inthe list according to the temporal distance result in sorted referencepictures in the order of increasing temporal distance to the currentpicture.

FIG. 25 is a flowchart which shows the second embodiment of the secondpredetermined scheme for a process of performing sorting on thereference picture list in the video encoding process and the videodecoding process using the second or third embodiment of the resilientpicture referencing scheme according to the present disclosure. First, amodule 2500 selects a first reference picture set including one or morekey pictures. Next, a module 2502 selects a second reference picture setincluding reference pictures not included in the first reference pictureset. A module 2504 then places the first reference picture set at thetop of a reference picture list according to the temporal distance tothe current picture. Lastly, a module 2506 places the second referencepicture set in the list behind the first reference picture set accordingto the temporal distance to the current picture. In one possibleimplementation of the second predetermined sorting scheme, the steps ofplacing reference pictures in the list according to the temporaldistance result in the sorted reference pictures in the order ofincreasing temporal distance to the current picture.

FIG. 26 is a flowchart which shows the third embodiment of the secondpredetermined scheme for the process of performing sorting on thereference picture list in the video encoding process and the decodingprocess using the second or third embodiment of the resilient picturereferencing scheme according to the present disclosure. A module 2600places reference pictures in the reference picture list according to thetemporal distance to the current picture, regardless of theclassification whether a picture is the key picture or not. In onepossible implementation of the second predetermined sorting scheme, thesteps of placing reference pictures in the list according to thetemporal distance result in the sorted reference pictures in the orderof increasing temporal distance to the current picture.

FIG. 27 is a block diagram which shows an example of a video encodingapparatus using the second embodiment of the resilient picturereferencing scheme according to the present disclosure. The videoencoding apparatus includes a classification determining unit 2700, amemory unit 2702, a first selection unit 2704, a second selection unit2714, a third selection unit 2716, a list creation unit 2706, a firstswitch unit 2708, a second switch unit 2724, a boundary identifying unit2710, a third switch unit 2712, a fourth switch unit 2718, a list addingunit 2720, a list sorting unit 2722, a motion estimation unit 2726, amotion prediction unit 2728, and a writing unit 2730.

As shown in FIG. 27, the motion estimation unit 2726 reads a block D2735of an image sample and one or more reference picture list D2733, andoutputs a motion vector set D2737. The motion prediction unit 2728 readsthe motion vector set D2737 and the reference picture list D2733, andoutputs a block D2739 of a predicted sample.

The classification determining unit 2700 reads the input data D2701 andperforms processing thereon to produce a classification signal D2703indicating whether a picture is the key picture or not and output dataD2741. The output data D2741 is written by the writing unit 2730 into acoded video bitstream D2743.

In one possible implementation of the present disclosure using the firstembodiment of the process for determining the classification indicatingwhether a picture is the key picture or not in the video decodingprocess as described referring to FIG. 10, the input data D2701 is aflag indicating the classification on whether the coded picture is thekey picture or not. According to the present embodiment, theclassification determining unit 2700 simply passes the flag as both itsoutputs, i.e., the classification signal D2703 and the output dataD2741.

In another possible implementation of the present disclosure using thesecond embodiment of the process for determining the classificationindicating whether a picture is the key picture or not in the videodecoding process as described referring to FIG. 13, the input data D2701is the temporal level of the coded picture. Using the temporal level ofthe coded picture, the classification determining unit 2700 determinesand outputs the classification signal D2703 indicating whether a pictureis the key picture or not. According to this embodiment, theclassification determining unit 2700 also sends, as the output dataD2741, the temporal level of a coded picture.

In yet another possible implementation of the present disclosure usingthe third embodiment of the process for determining the classificationindicating whether a picture is the key picture or not in the videodecoding process as described referring to FIG. 16, the input data D2701may be the period of key pictures. Using the period of key pictures, theclassification determining unit 2700 determines and outputs theclassification signal D2703 indicating whether a picture is the keypicture or not. According to this embodiment, the classificationdetermining unit 2700 also sends, as the output data D2741, the periodof key pictures.

The first selection unit 2704 reads stored reference pictures D2705 fromthe memory unit 2702 and passes a key reference picture D2707 to thelist creation unit 2706, which creates one or more reference picturelists D2709. The first switch unit 2708 uses the classification signalD2703 as a control signal for switching the destination of the referencepicture lists D2709 between the second switch unit 2724 when theclassification signal D2703 indicates the key picture, and the listadding unit 2720 when the classification signal D2703 indicates thenon-key picture.

The list adding unit 2720 adds a selected non-key reference picturegroup D2727 to the reference picture list D2713, and outputs an extendedreference picture list D2729. The list sorting unit 2722 then sorts theextended reference picture list D2729 and outputs a sorted referencepicture list D2731. Based on the control signal D2703, the second switchunit 2724 switches the reference picture list to be sent as a finalreference picture list D2733, between the reference picture list D2711and the reference picture list D2731.

The boundary identifying unit 2710 reads the key reference picture D2707and identifies two boundary pictures D2717 including a first and asecond boundary pictures. The boundary identifying unit 2710 alsooutputs a control signal D2715 indicating whether the second boundarypicture is present or not. When the control signal D2715 indicates thatthe second boundary picture is not present, the third switch unit 2712performs switching so as to send the boundary picture D2717 to thesecond selection unit 2714. The second selection unit 2714 reads astored reference picture D2705 from the memory unit 2702 and a boundarypicture D2719, then outputs a selected non-key reference picture groupD2723. When the control signal D2715 indicates that the second boundarypicture is not present, the third switch unit 2712 performs switching soas to send the boundary pictures D2717 to the third selection unit 2716.The third selection unit 2716 reads the stored reference pictures D2705from the memory unit 2702 and the boundary pictures D2721, then outputsa selected non-key-reference pictures group D2725. The fourth switchunit 2718 uses the control signal D2715 to perform switching of anoutput to be sent as the selected non-key reference picture group D2727,between the output of the second selection unit 2714 and the output ofthe third selection unit 2716.

FIG. 28 is a block diagram which shows an example of a video decodingapparatus using the second embodiment of the resilient picturereferencing scheme according to the present disclosure. The videodecoding apparatus includes a classification determining unit 2800, amemory unit 2802, a first selection unit 2804, a second selection unit2814, a third selection unit 2816, a list creation unit 2806, a firstswitch unit 2808, a second switch unit 2824, a boundary identifying unit2810, a third switch unit 2812, a fourth switch unit 2818, a list addingunit 2820, a list sorting unit 2822, and a motion prediction unit 2826.

As shown in FIG. 28, the motion prediction unit 2826 reads a decodedmotion vector set D2835, one or more reference picture lists D2833, andoutputs a block D2837 of a predicted sample.

The classification determining unit 2800 reads the input data D2801 andperforms processing thereon to produce a classification signal D2803indicating whether a picture is the key picture or not.

In one possible implementation of the present disclosure using the firstembodiment of the process for determining the classification indicatingwhether a picture is the key picture or not in the video decodingprocess as described referring to FIG. 11, the parsed input data D2801is a parsed flag indicating a classification on whether the codedpicture is the key picture or not. According to this embodiment, theclassification determining unit 2800 simply outputs the parsed flag asthe classification signal D2803.

In another possible implementation of the present disclosure using thesecond embodiment of the process for determining the classificationindicating whether a picture is the key picture or not in the videodecoding process as described referring to FIG. 14, the parsed inputdata D2801 is the temporal level of the coded picture. Using the parsedtemporal level of the coded picture, the classification determining unit2800 determines and outputs the classification signal D2803 indicatingwhether a picture is the key picture or not.

In yet another possible implementation of the present disclosure usingthe third embodiment of the process for determining the classificationindicating whether a picture is the key picture or not as describedreferring to FIG. 17, the parsed input data D2801 is the parsed periodof key pictures. Using the parsed period of key pictures, theclassification determining unit 2800 determines and outputs theclassification signal D2803 indicating whether a picture is the keypicture or not.

The first selection unit 2804 reads a stored reference picture D2805from the memory unit 2802 and passes a key reference pictures D2807 tothe list creation unit 2806, which creates one or more reference picturelists D2809. The first switch unit 2808 uses the classification signalD2803 as a control signal for switching the destination of the referencepicture lists D2809 between the second switch unit 2824 when theclassification signal D2803 indicates the key picture, and the listadding unit 2820 when the classification signal D2803 indicates thenon-key picture. The list adding unit 2820 adds a selected non-keyreference picture group D2827 to a reference picture list D2813, andoutputs an extended reference picture list D2829. The list sorting unit2822 then sorts the extended reference picture list D2829 and outputs asorted reference picture list D2831. Based on the control signal D2803,the second switch unit 2824 performs switching of a reference picturelist to be sent as a final reference picture list D2833 between thereference picture list D2811 and the reference picture list D2813.

The boundary identifying unit 2810 reads the key reference picture D2807and identifies two boundary pictures D2817 including a first and asecond boundary pictures. The boundary identifying unit 2810 alsooutputs a control signal D2815 indicating whether the second boundarypicture is present or not. When the control signal D2815 indicates thatthe second boundary picture is not present, the third switch unit 2812performs switching so as to send the boundary picture D2817 to thesecond selection unit 2814. The second selection unit 2814 reads thestored reference picture D2805 from the memory unit 2802 and a boundarypicture D2819, then outputs a selected non-key reference picture groupD2823. When the control signal D2815 indicates that the second boundarypicture is not present, the third switch unit 2812 performs switching soas to send the boundary pictures D2817 to the third selection unit 2816.The third selection unit 2816 reads the stored reference picture D2805from the memory unit 2802 and a boundary pictures D2821, then outputs aselected non-key reference picture group D2825. The fourth switch unit2818 uses the control signal D2815 to perform switching of an output tobe sent as the selected non-key reference picture group D2827, betweenthe output of the second selection unit 2814 and the output of the thirdselection unit 2816.

FIG. 29 is a flowchart which shows a video encoding process using thethird embodiment of a resilient picture referencing scheme according tothe present disclosure. A module 2900 determines the classificationindicating whether a picture is the key picture or not. Detailedembodiments of the step for determining the classification indicatingwhether a picture is the key picture or not are given in earlierdescriptions in this specification. A module 2902 then constructs afirst reference picture list using the temporal distance to the currentpicture and the classification indicating whether a picture is the keypicture or not. A module 2904 constructs a second reference picture listusing the temporal distance to the current picture and theclassification indicating whether a picture is the key picture or not.Detailed embodiments of the step for constructing a reference picturelist using the temporal distance to the current picture and theclassification are given in earlier descriptions in this specification.A module 2906 then reorders the first reference picture list so as to beequivalent to the second reference picture list. Next, a module 2908writes a plurality of parameters specifying the steps for performingreordering in the first reference picture list into a header of a codedslice of the current picture. A motion estimation process is thenperformed on a block of an image sample using the first referencepicture list in a module 2910, and a motion prediction process isperformed on the block of the image sample using the reference picturelist in a module 2912.

FIG. 30 is a block diagram which shows an example of a video encodingapparatus using the third embodiment of the resilient picturereferencing scheme according to the present disclosure. The videoencoding apparatus includes a classification determining unit 3000, amemory unit 3002, a first selection unit 3004, a second selection unit3014, a third selection unit 3016, a first list creation unit 3030, asecond list creation unit 3006, a first switch unit 3008, a secondswitch unit 3024, a boundary identifying unit 3010, a third switch unit3012, a fourth switch unit 3018, a list adding unit 3020, a list sortingunit 3022, a motion estimation unit 3026, a motion prediction unit 3028,a list reordering unit 3032, and a writing unit 3034.

As shown in FIG. 30, the motion estimation unit 3026 reads a block D3035of an image sample and one or more reference picture lists D3043, andoutputs a motion vector set D3037. The motion prediction unit 3028 readsthe motion vector set D3037, the reference picture lists D3043, andoutputs a block D3039 of a predicted sample.

The classification determining unit 3000 reads input data D3001 andperforms processing thereon to produce a classification signal D3003indicating whether a picture is the key picture or not and output dataD3042.

In one possible implementation of the present disclosure using the firstembodiment of the process for determining the classification indicatingwhether a picture is the key picture or not in the video encodingprocess as described referring to FIG. 10, the input data D2701 is aflag indicating the classification on whether the coded picture is thekey picture or not. According to this embodiment, the classificationdetermining unit 3000 simply passes the flag as both its outputs, i.e.,the classification signal D3003 and the output data D3042.

In another possible implementation of the present disclosure using thesecond embodiment of the process for determining the classificationindicating whether a picture is the key picture or not in the videodecoding process as described referring to FIG. 13, the input data D3001is the temporal level of the coded picture. Using the temporal level ofthe coded picture, the classification determining unit 3000 determinesand outputs the classification signal D3003 indicating whether a pictureis the key picture or not. According to this embodiment, theclassification determining unit 3000 also sends, as the output dataD3042, the temporal level of the coded picture.

In yet another possible implementation of the present disclosure usingthe third embodiment of the process for determining the classificationindicating whether a picture is the key picture or not in the videoencoding process as described referring to FIG. 16, the input data D3001may be the period of key pictures. Using the period of key pictures, theclassification determining unit 3000 determines and outputs theclassification signal D3003 indicating whether a picture is the keypicture or not. According to the present embodiment, the classificationdetermining unit 3000 also sends, as the output data D3042, the periodof key pictures.

The first list creation unit 3030 reads a stored reference picture D3005from the memory unit 3002 and creates one or more initial referencepicture lists D3041. The list reordering unit 3032 takes the initialreference picture lists D3041 and the modified reference picture listD3033, then produces a final reordered reference picture list D3043 foruse by the motion estimation unit 3026 and the motion prediction unit3028. The list reordering unit 3032 also outputs a reordering step D3045performed on the initial reference lists D3041 to become equivalent asthe modified reference picture list D3033. The writing unit 3034 writesoutput data D3042 from the classification determining unit 3000 and thereordering steps D3045 into a coded video bitstream D3047.

The construction of the modified reference picture list D3033 isperformed as follows. The first selection unit 3004 reads the storedreference picture D3005 from the memory unit 3002 and passes the keyreference pictures D3007 to the second list creation unit 3006, whichcreates one or more reference picture lists D3009. The first switch unit3008 uses the classification signal D3003 as a control signal forswitching the destination of the reference picture lists D3009 betweenthe second switch unit 3024 when the classification signal D3003indicates the key picture, and the list adding unit 3020 when theclassification signal D3003 indicates the non-key picture. The listadding unit 3020 adds a selected reference picture group D3027 to areference picture list D3013, and outputs an extended reference picturelist D3029. The list sorting unit 3022 then sorts the extended referencepicture list D3029 and outputs a sorted reference picture list D3031.Based on the control signal D3003, the second switch unit 3024 performsswitching of a reference picture list to be sent as a modified referencepicture list D3033, between the reference picture list D3011 and thesorted reference picture list D3031.

The boundary identifying unit 3010 reads the key reference picture D3007and identifies two boundary pictures D3017 including a first and asecond boundary pictures. The boundary identifying unit 3010 alsooutputs a control signal D3015 indicating whether the second boundarypicture is present or not. When the control signal D3015 indicates thatthe second boundary picture is not present, the third switch unit 3012performs switching so as to send the boundary picture D3017 to thesecond selection unit 3014. The second selection unit 3014 reads thestored reference picture D3005 from the memory unit 3002 and a boundarypicture D3019, then outputs a selected non-key reference picture groupD3023. When the control signal D3015 indicates that the second boundarypicture is not present, the third switch unit 3012 sends the boundarypicture D3017 to the third selection unit 3016. The third selection unit3016 reads the stored reference picture D3005 from the memory unit 3002and a boundary picture D3021, then outputs a selected non-key referencepicture group D3025. The fourth switch unit 3018 uses the control signalD3015 to perform switching of an output to be sent as a selected non-keyreference picture group D3037, between the output of the secondselection unit 3014 and the output of the third selection unit 3016.

FIG. 31 is a diagram which shows a location of the parameters to specifya reference list reordering step in a slice header of a coded videobitstream. Using the plurality of reference list reordering parameterswhich are parsed from a coded video bitstream, a compliant videodecoding apparatus reorders a predetermined reference picture list andproduces an equivalent modified reference picture list to be used in theencoding process.

Fourth Embodiment

The processing described in each of embodiments can be simplyimplemented in an independent computer system, by recording, in arecording medium, a program for implementing the configurations of themoving picture coding method (image coding method) and the movingpicture decoding method (image decoding method) described in each ofembodiments. The recording media may be any recording media as long asthe program can be recorded, such as a magnetic disk, an optical disk, amagnetic optical disk, an IC card, and a semiconductor memory.

Hereinafter, the applications to the moving picture coding method (imagecoding method) and the moving picture decoding method (image decodingmethod) described in each of embodiments and systems using thereof willbe described. The system has a feature of having an image coding anddecoding apparatus that includes an image coding apparatus using theimage coding method and an image decoding apparatus using the imagedecoding method. Other configurations in the system can be changed asappropriate depending on the cases.

FIG. 32 illustrates an overall configuration of a content providingsystem ex100 for implementing content distribution services. The areafor providing communication services is divided into cells of desiredsize, and base stations ex106, ex107, ex108, ex109, and ex110 which arefixed wireless stations are placed in each of the cells.

The content providing system ex100 is connected to devices, such as acomputer ex111, a personal digital assistant (PDA) ex112, a cameraex113, a cellular phone ex114 and a game machine ex115, via the Internetex101, an Internet service provider ex102, a telephone network ex104, aswell as the base stations ex106 to ex110, respectively.

However, the configuration of the content providing system ex100 is notlimited to the configuration shown in FIG. 32, and a combination inwhich any of the elements are connected is acceptable. In addition, eachdevice may be directly connected to the telephone network ex104, ratherthan via the base stations ex106 to ex110 which are the fixed wirelessstations. Furthermore, the devices may be interconnected to each othervia a short distance wireless communication and others.

The camera ex113, such as a digital video camera, is capable ofcapturing video. A camera ex116, such as a digital camera, is capable ofcapturing both still images and video. Furthermore, the cellular phoneex114 may be the one that meets any of the standards such as GlobalSystem for Mobile Communications (GSM) (registered trademark), CodeDivision Multiple Access (CDMA), Wideband-Code Division Multiple Access(W-CDMA), Long Term Evolution (LTE), and High Speed Packet Access(HSPA). Alternatively, the cellular phone ex114 may be a PersonalHandyphone System (PHS).

In the content providing system ex100, a streaming server ex103 isconnected to the camera ex113 and others via the telephone network ex104and the base station ex109, which enables distribution of images of alive show and others. In such a distribution, a content (for example,video of a music live show) captured by the user using the camera ex113is coded as described above in each of embodiments (i.e., the camerafunctions as the image coding apparatus according to an aspect of thepresent disclosure), and the coded content is transmitted to thestreaming server ex103. On the other hand, the streaming server ex103carries out stream distribution of the transmitted content data to theclients upon their requests. The clients include the computer ex111, thePDA ex112, the camera ex113, the cellular phone ex114, and the gamemachine ex115 that are capable of decoding the above-mentioned codeddata. Each of the devices that have received the distributed datadecodes and reproduces the coded data (i.e., functions as the imagedecoding apparatus according to an aspect of the present disclosure).

The captured data may be coded by the camera ex113 or the streamingserver ex103 that transmits the data, or the coding processes may beshared between the camera ex113 and the streaming server ex103.Similarly, the distributed data may be decoded by the clients or thestreaming server ex103, or the decoding processes may be shared betweenthe clients and the streaming server ex103. Furthermore, the data of thestill images and video captured by not only the camera ex113 but alsothe camera ex116 may be transmitted to the streaming server ex103through the computer ex111. The coding processes may be performed by thecamera ex116, the computer ex111, or the streaming server ex103, orshared among them.

Furthermore, the coding and decoding processes may be performed by anLSI ex500 generally included in each of the computer ex111 and thedevices. The LSI ex500 may be configured of a single chip or a pluralityof chips. Software for coding and decoding video may be integrated intosome type of a recording medium (such as a CD-ROM, a flexible disk, anda hard disk) that is readable by the computer ex111 and others, and thecoding and decoding processes may be performed using the software.Furthermore, when the cellular phone ex114 is equipped with a camera,the video data obtained by the camera may be transmitted. The video datais data coded by the LSI ex500 included in the cellular phone ex114.

Furthermore, the streaming server ex103 may be composed of servers andcomputers, and may decentralize data and process the decentralized data,record, or distribute data.

As described above, the clients may receive and reproduce the coded datain the content providing system ex100. In other words, the clients canreceive and decode information transmitted by the user, and reproducethe decoded data in real time in the content providing system ex100, sothat the user who does not have any particular right and equipment canimplement personal broadcasting.

Aside from the example of the content providing system ex100, at leastone of the moving picture coding apparatus (image coding apparatus) andthe moving picture decoding apparatus (image decoding apparatus)described in each of embodiments may be implemented in a digitalbroadcasting system ex200 illustrated in FIG. 33. More specifically, abroadcast station ex201 communicates or transmits, via radio waves to abroadcast satellite ex202, multiplexed data obtained by multiplexingaudio data and others onto video data. The video data is data coded bythe moving picture coding method described in each of embodiments (i.e.,data coded by the image coding apparatus according to an aspect of thepresent disclosure). Upon receipt of the multiplexed data, the broadcastsatellite ex202 transmits radio waves for broadcasting. Then, a home-useantenna ex204 with a satellite broadcast reception function receives theradio waves. Next, a device such as a television (receiver) ex300 and aset top box (STB) ex217 decodes the received multiplexed data, andreproduces the decoded data (i.e., functions as the image decodingapparatus according to an aspect of the present disclosure).

Furthermore, a reader/recorder ex218 (i) reads and decodes themultiplexed data recorded on a recording medium ex215, such as a DVD anda BD, or (i) codes video signals in the recording medium ex215, and insome cases, writes data obtained by multiplexing an audio signal on thecoded data. The reader/recorder ex218 can include the moving picturedecoding apparatus or the moving picture coding apparatus as shown ineach of embodiments. In this case, the reproduced video signals aredisplayed on the monitor ex219, and can be reproduced by another deviceor system using the recording medium ex215 on which the multiplexed datais recorded. It is also possible to implement the moving picturedecoding apparatus in the set top box ex217 connected to the cable ex203for a cable television or to the antenna ex204 for satellite and/orterrestrial broadcasting, so as to display the video signals on themonitor ex219 of the television ex300. The moving picture decodingapparatus may be implemented not in the set top box but in thetelevision ex300.

FIG. 34 illustrates the television (receiver) ex300 that uses the movingpicture coding method and the moving picture decoding method describedin each of embodiments. The television ex300 includes: a tuner ex301that obtains or provides multiplexed data obtained by multiplexing audiodata onto video data, through the antenna ex204 or the cable ex203,etc., that receives a broadcast; a modulation/demodulation unit ex302that demodulates the received multiplexed data or modulates data intomultiplexed data to be supplied outside; and amultiplexing/demultiplexing unit ex303 that demultiplexes the modulatedmultiplexed data into video data and audio data, or multiplexes videodata and audio data coded by a signal processing unit ex306 into data.

The television ex300 further includes: a signal processing unit ex306including an audio signal processing unit ex304 and a video signalprocessing unit ex305 that decode audio data and video data and codeaudio data and video data, respectively (which function as the imagecoding apparatus and the image decoding apparatus according to theaspects of the present disclosure); and an output unit ex309 including aspeaker ex307 that provides the decoded audio signal, and a display unitex308 that displays the decoded video signal, such as a display.Furthermore, the television ex300 includes an interface unit ex317including an operation input unit ex312 that receives an input of a useroperation. Furthermore, the television ex300 includes a control unitex310 that controls overall each constituent element of the televisionex300, and a power supply circuit unit ex311 that supplies power to eachof the elements. Other than the operation input unit ex312, theinterface unit ex317 may include: a bridge ex313 that is connected to anexternal device, such as the reader/recorder ex218; a slot unit ex314for enabling attachment of the recording medium ex216, such as an SDcard; a driver ex315 to be connected to an external recording medium,such as a hard disk; and a modem ex316 to be connected to a telephonenetwork. Here, the recording medium ex216 can electrically recordinformation using a non-volatile/volatile semiconductor memory elementfor storage. The constituent elements of the television ex300 areconnected to each other through a synchronous bus.

First, the configuration in which the television ex300 decodesmultiplexed data obtained from outside through the antenna ex204 andothers and reproduces the decoded data will be described. In thetelevision ex300, upon a user operation through a remote controllerex220 and others, the multiplexing/demultiplexing unit ex303demultiplexes the multiplexed data demodulated by themodulation/demodulation unit ex302, under control of the control unitex310 including a CPU. Furthermore, the audio signal processing unitex304 decodes the demultiplexed audio data, and the video signalprocessing unit ex305 decodes the demultiplexed video data, using thedecoding method described in each of embodiments, in the televisionex300. The output unit ex309 provides the decoded video signal and audiosignal outside, respectively. When the output unit ex309 provides thevideo signal and the audio signal, the signals may be temporarily storedin buffers ex318 and ex319, and others so that the signals arereproduced in synchronization with each other. Furthermore, thetelevision ex300 may read multiplexed data not through a broadcast andothers but from the recording media ex215 and ex216, such as a magneticdisk, an optical disk, and a SD card. Next, a configuration in which thetelevision ex300 codes an audio signal and a video signal, and transmitsthe data outside or writes the data on a recording medium will bedescribed. In the television ex300, upon a user operation through theremote controller ex220 and others, the audio signal processing unitex304 codes an audio signal, and the video signal processing unit ex305codes a video signal, under control of the control unit ex310 using thecoding method described in each of embodiments. Themultiplexing/demultiplexing unit ex303 multiplexes the coded videosignal and audio signal, and provides the resulting signal outside. Whenthe multiplexing/demultiplexing unit ex303 multiplexes the video signaland the audio signal, the signals may be temporarily stored in thebuffers ex320 and ex321, and others so that the signals are reproducedin synchronization with each other. Here, the buffers ex318, ex319,ex320, and ex321 may be plural as illustrated, or at least one buffermay be shared in the television ex300. Furthermore, data may be storedin a buffer so that the system overflow and underflow may be avoidedbetween the modulation/demodulation unit ex302 and themultiplexing/demultiplexing unit ex303, for example.

Furthermore, the television ex300 may include a configuration forreceiving an AV input from a microphone or a camera other than theconfiguration for obtaining audio and video data from a broadcast or arecording medium, and may code the obtained data. Although thetelevision ex300 can code, multiplex, and provide outside data in thedescription, it may be capable of only receiving, decoding, andproviding outside data but not the coding, multiplexing, and providingoutside data.

Furthermore, when the reader/recorder ex218 reads or writes multiplexeddata from or on a recording medium, one of the television ex300 and thereader/recorder ex218 may decode or code the multiplexed data, and thetelevision ex300 and the reader/recorder ex218 may share the decoding orcoding.

As an example, FIG. 35 illustrates a configuration of an informationreproducing/recording unit ex400 when data is read or written from or onan optical disk. The information reproducing/recording unit ex400includes constituent elements ex401, ex402, ex403, ex404, ex405, ex406,and ex407 to be described hereinafter. The optical head ex401 irradiatesa laser spot in a recording surface of the recording medium ex215 thatis an optical disk to write information, and detects reflected lightfrom the recording surface of the recording medium ex215 to read theinformation. The modulation recording unit ex402 electrically drives asemiconductor laser included in the optical head ex401, and modulatesthe laser light according to recorded data. The reproductiondemodulating unit ex403 amplifies a reproduction signal obtained byelectrically detecting the reflected light from the recording surfaceusing a photo detector included in the optical head ex401, anddemodulates the reproduction signal by separating a signal componentrecorded on the recording medium ex215 to reproduce the necessaryinformation. The buffer ex404 temporarily holds the information to berecorded on the recording medium ex215 and the information reproducedfrom the recording medium ex215. The disk motor ex405 rotates therecording medium ex215. The servo control unit ex406 moves the opticalhead ex401 to a predetermined information track while controlling therotation drive of the disk motor ex405 so as to follow the laser spot.The system control unit ex407 controls overall the informationreproducing/recording unit ex400. The reading and writing processes canbe implemented by the system control unit ex407 using variousinformation stored in the buffer ex404 and generating and adding newinformation as necessary, and by the modulation recording unit ex402,the reproduction demodulating unit ex403, and the servo control unitex406 that record and reproduce information through the optical headex401 while being operated in a coordinated manner. The system controlunit ex407 includes, for example, a microprocessor, and executesprocessing by causing a computer to execute a program for read andwrite.

Although the optical head ex401 irradiates a laser spot in thedescription, it may perform high-density recording using near fieldlight.

FIG. 36 illustrates the recording medium ex215 that is the optical disk.On the recording surface of the recording medium ex215, guide groovesare spirally formed, and an information track ex230 records, in advance,address information indicating an absolute position on the diskaccording to change in a shape of the guide grooves. The addressinformation includes information for determining positions of recordingblocks ex231 that are a unit for recording data. Reproducing theinformation track ex230 and reading the address information in anapparatus that records and reproduces data can lead to determination ofthe positions of the recording blocks. Furthermore, the recording mediumex215 includes a data recording area ex233, an inner circumference areaex232, and an outer circumference area ex234. The data recording areaex233 is an area for use in recording the user data. The innercircumference area ex232 and the outer circumference area ex234 that areinside and outside of the data recording area ex233, respectively arefor specific use except for recording the user data. The informationreproducing/recording unit 400 reads and writes coded audio, coded videodata, or multiplexed data obtained by multiplexing the coded audio andvideo data, from and on the data recording area ex233 of the recordingmedium ex215.

Although an optical disk having a layer, such as a DVD and a BD isdescribed as an example in the description, the optical disk is notlimited to such, and may be an optical disk having a multilayerstructure and capable of being recorded on a part other than thesurface. Furthermore, the optical disk may have a structure formultidimensional recording/reproduction, such as recording ofinformation using light of colors with different wavelengths in the sameportion of the optical disk and for recording information havingdifferent layers from various angles.

Furthermore, a car ex210 having an antenna ex205 can receive data fromthe satellite ex202 and others, and reproduce video on a display devicesuch as a car navigation system ex211 set in the car ex210, in thedigital broadcasting system ex200. Here, a configuration of the carnavigation system ex211 will be a configuration, for example, includinga GPS receiving unit from the configuration illustrated in FIG. 34. Thesame will be true for the configuration of the computer ex111, thecellular phone ex114, and others.

FIG. 37A illustrates the cellular phone ex114 that uses the movingpicture coding method and the moving picture decoding method describedin embodiments. The cellular phone ex114 includes: an antenna ex350 fortransmitting and receiving radio waves through the base station ex110; acamera unit ex365 capable of capturing moving and still images; and adisplay unit ex358 such as a liquid crystal display for displaying thedata such as decoded video captured by the camera unit ex365 or receivedby the antenna ex350. The cellular phone ex114 further includes: a mainbody unit including an operation key unit ex366; an audio output unitex357 such as a speaker for output of audio; an audio input unit ex356such as a microphone for input of audio; a memory unit ex367 for storingcaptured video or still pictures, recorded audio, coded or decoded dataof the received video, the still pictures, e-mails, or others; and aslot unit ex364 that is an interface unit for a recording medium thatstores data in the same manner as the memory unit ex367.

Next, an example of a configuration of the cellular phone ex114 will bedescribed with reference to FIG. 37B. In the cellular phone ex114, amain control unit ex360 designed to control overall each unit of themain body including the display unit ex358 as well as the operation keyunit ex366 is connected mutually, via a synchronous bus ex370, to apower supply circuit unit ex361, an operation input control unit ex362,a video signal processing unit ex355, a camera interface unit ex363, aliquid crystal display (LCD) control unit ex359, amodulation/demodulation unit ex352, a multiplexing/demultiplexing unitex353, an audio signal processing unit ex354, the slot unit ex364, andthe memory unit ex367.

When a call-end key or a power key is turned ON by a user's operation,the power supply circuit unit ex361 supplies the respective units withpower from a battery pack so as to activate the cell phone ex114.

In the cellular phone ex114, the audio signal processing unit ex354converts the audio signals collected by the audio input unit ex356 invoice conversation mode into digital audio signals under the control ofthe main control unit ex360 including a CPU, ROM, and RAM. Then, themodulation/demodulation unit ex352 performs spread spectrum processingon the digital audio signals, and the transmitting and receiving unitex351 performs digital-to-analog conversion and frequency conversion onthe data, so as to transmit the resulting data via the antenna ex350.Also, in the cellular phone ex114, the transmitting and receiving unitex351 amplifies the data received by the antenna ex350 in voiceconversation mode and performs frequency conversion and theanalog-to-digital conversion on the data. Then, themodulation/demodulation unit ex352 performs inverse spread spectrumprocessing on the data, and the audio signal processing unit ex354converts it into analog audio signals, so as to output them via theaudio output unit ex357.

Furthermore, when an e-mail in data communication mode is transmitted,text data of the e-mail inputted by operating the operation key unitex366 and others of the main body is sent out to the main control unitex360 via the operation input control unit ex362. The main control unitex360 causes the modulation/demodulation unit ex352 to perform spreadspectrum processing on the text data, and the transmitting and receivingunit ex351 performs the digital-to-analog conversion and the frequencyconversion on the resulting data to transmit the data to the basestation ex110 via the antenna ex350. When an e-mail is received,processing that is approximately inverse to the processing fortransmitting an e-mail is performed on the received data, and theresulting data is provided to the display unit ex358.

When video, still images, or video and audio in data communication modeis or are transmitted, the video signal processing unit ex355 compressesand codes video signals supplied from the camera unit ex365 using themoving picture coding method shown in each of embodiments (i.e.,functions as the image coding apparatus according to the aspect of thepresent disclosure), and transmits the coded video data to themultiplexing/demultiplexing unit ex353. In contrast, during when thecamera unit ex365 captures video, still images, and others, the audiosignal processing unit ex354 codes audio signals collected by the audioinput unit ex356, and transmits the coded audio data to themultiplexing/demultiplexing unit ex353.

The multiplexing/demultiplexing unit ex353 multiplexes the coded videodata supplied from the video signal processing unit ex355 and the codedaudio data supplied from the audio signal processing unit ex354, using apredetermined method. Then, the modulation/demodulation unit(modulation/demodulation circuit unit) ex352 performs spread spectrumprocessing on the multiplexed data, and the transmitting and receivingunit ex351 performs digital-to-analog conversion and frequencyconversion on the data so as to transmit the resulting data via theantenna ex350.

When receiving data of a video file which is linked to a Web page andothers in data communication mode or when receiving an e-mail with videoand/or audio attached, in order to decode the multiplexed data receivedvia the antenna ex350, the multiplexing/demultiplexing unit ex353demultiplexes the multiplexed data into a video data bit stream and anaudio data bit stream, and supplies the video signal processing unitex355 with the coded video data and the audio signal processing unitex354 with the coded audio data, through the synchronous bus ex370. Thevideo signal processing unit ex355 decodes the video signal using amoving picture decoding method corresponding to the moving picturecoding method shown in each of embodiments (i.e., functions as the imagedecoding apparatus according to the aspect of the present disclosure),and then the display unit ex358 displays, for instance, the video andstill images included in the video file linked to the Web page via theLCD control unit ex359. Furthermore, the audio signal processing unitex354 decodes the audio signal, and the audio output unit ex357 providesthe audio.

Furthermore, similarly to the television ex300, it is possible for aterminal such as the cellular phone ex114 to have 3 types ofimplementation configurations including not only (i) a transmitting andreceiving terminal including both a coding apparatus and a decodingapparatus, but also (ii) a transmitting terminal including only a codingapparatus and (iii) a receiving terminal including only a decodingapparatus. Although the digital broadcasting system ex200 receives andtransmits the multiplexed data obtained by multiplexing audio data ontovideo data in the description, the multiplexed data may be data obtainedby multiplexing not audio data but character data related to video ontovideo data, and may be not multiplexed data but video data itself.

As such, the moving picture coding method and the moving picturedecoding method in each of embodiments can be used in any of the devicesand systems described. Thus, the advantages described in each ofembodiments can be obtained.

Furthermore, the present disclosure is not limited to embodiments, andvarious modifications and revisions are possible without departing fromthe scope of the present disclosure.

Fifth Embodiment

Video data can be generated by switching, as necessary, between (i) themoving picture coding method or the moving picture coding apparatusshown in each of embodiments and (ii) a moving picture coding method ora moving picture coding apparatus in conformity with a differentstandard, such as MPEG-2, MPEG-4 AVC, and VC-1.

Here, when a plurality of video data that conforms to the differentstandards is generated and is then decoded, the decoding methods need tobe selected to conform to the different standards. However, since thestandard to which each of the plurality of the video data to be decodedconforms cannot be detected, there is a problem that an appropriatedecoding method cannot be selected.

In view of the above, multiplexed data obtained by multiplexing audiodata and others onto video data has a structure including identificationinformation indicating to which standard the video data conforms. Thespecific structure of the multiplexed data including the video datagenerated in the moving picture coding method and by the moving picturecoding apparatus shown in each of embodiments will be hereinafterdescribed. The multiplexed data is a digital stream in the MPEG-2Transport Stream format.

FIG. 38 illustrates a structure of the multiplexed data. As illustratedin FIG. 38, the multiplexed data can be obtained by multiplexing atleast one of a video stream, an audio stream, a presentation graphicsstream (PG), and an interactive graphics stream. The video streamrepresents primary video and secondary video of a movie, the audiostream (IG) represents a primary audio part and a secondary audio partto be mixed with the primary audio part, and the presentation graphicsstream represents subtitles of the movie. Here, the primary video isnormal video to be displayed on a screen, and the secondary video isvideo to be displayed on a smaller window in the primary video.Furthermore, the interactive graphics stream represents an interactivescreen to be generated by arranging the GUI components on a screen. Thevideo stream is coded in the moving picture coding method or by themoving picture coding apparatus shown in each of embodiments, or in amoving picture coding method or by a moving picture coding apparatus inconformity with a conventional standard, such as MPEG-2, MPEG-4 AVC, andVC-1. The audio stream is coded in accordance with a standard, such asDolby-AC-3, Dolby Digital Plus, MLP, DTS, DTS-HD, and linear PCM.

Each stream included in the multiplexed data is identified by PID. Forexample, 0x1011 is allocated to the video stream to be used for video ofa movie, 0x1100 to 0x111F are allocated to the audio streams, 0x1200 to0x121F are allocated to the presentation graphics streams, 0x1400 to0x141F are allocated to the interactive graphics streams, 0x1B00 to0x1B1F are allocated to the video streams to be used for secondary videoof the movie, and 0x1A00 to 0x1A1F are allocated to the audio streams tobe used for the secondary audio to be mixed with the primary audio.

FIG. 39 schematically illustrates how data is multiplexed. First, avideo stream ex235 composed of video frames and an audio stream ex238composed of audio frames are transformed into a stream of PES packetsex236 and a stream of PES packets ex239, and further into TS packetsex237 and TS packets ex240, respectively. Similarly, data of apresentation graphics stream ex241 and data of an interactive graphicsstream ex244 are transformed into a stream of PES packets ex242 and astream of PES packets ex245, and further into TS packets ex243 and TSpackets ex246, respectively. These TS packets are multiplexed into astream to obtain multiplexed data ex247.

FIG. 40 illustrates how a video stream is stored in a stream of PESpackets in more detail. The first bar in FIG. 40 shows a video framestream in a video stream. The second bar shows the stream of PESpackets. As indicated by arrows denoted as yy1, yy2, yy3, and yy4 inFIG. 40, the video stream is divided into pictures as I pictures, Bpictures, and P pictures each of which is a video presentation unit, andthe pictures are stored in a payload of each of the PES packets. Each ofthe PES packets has a PES header, and the PES header stores aPresentation Time-Stamp (PTS) indicating a display time of the picture,and a Decoding Time-Stamp (DTS) indicating a decoding time of thepicture.

FIG. 41 illustrates a format of TS packets to be finally written on themultiplexed data. Each of the TS packets is a 188-byte fixed lengthpacket including a 4-byte TS header having information, such as a PIDfor identifying a stream and a 184-byte TS payload for storing data. ThePES packets are divided, and stored in the TS payloads, respectively.When a BD ROM is used, each of the TS packets is given a 4-byteTP_Extra_Header, thus resulting in 192-byte source packets. The sourcepackets are written on the multiplexed data. The TP_Extra_Header storesinformation such as an Arrival_Time_Stamp (ATS). The ATS shows atransfer start time at which each of the TS packets is to be transferredto a PID filter. The source packets are arranged in the multiplexed dataas shown at the bottom of FIG. 41. The numbers incrementing from thehead of the multiplexed data are called source packet numbers (SPNs).

Each of the TS packets included in the multiplexed data includes notonly streams of audio, video, subtitles and others, but also a ProgramAssociation Table (PAT), a Program Map Table (PMT), and a Program ClockReference (PCR). The PAT shows what a PID in a PMT used in themultiplexed data indicates, and a PID of the PAT itself is registered aszero. The PMT stores PIDs of the streams of video, audio, subtitles andothers included in the multiplexed data, and attribute information ofthe streams corresponding to the PIDs. The PMT also has variousdescriptors relating to the multiplexed data. The descriptors haveinformation such as copy control information showing whether copying ofthe multiplexed data is permitted or not. The PCR stores STC timeinformation corresponding to an ATS showing when the PCR packet istransferred to a decoder, in order to achieve synchronization between anArrival Time Clock (ATC) that is a time axis of ATSs, and an System TimeClock (STC) that is a time axis of PTSs and DTSs.

FIG. 42 illustrates the data structure of the PMT in detail A PMT headeris disposed at the top of the PMT. The PMT header describes the lengthof data included in the PMT and others. A plurality of descriptorsrelating to the multiplexed data is disposed after the PMT header.Information such as the copy control information is described in thedescriptors. After the descriptors, a plurality of pieces of streaminformation relating to the streams included in the multiplexed data isdisposed. Each piece of stream information includes stream descriptorseach describing information, such as a stream type for identifying acompression codec of a stream, a stream PID, and stream attributeinformation (such as a frame rate or an aspect ratio). The streamdescriptors are equal in number to the number of streams in themultiplexed data.

When the multiplexed data is recorded on a recording medium and others,it is recorded together with multiplexed data information files.

Each of the multiplexed data information files is management informationof the multiplexed data as shown in FIG. 43. The multiplexed datainformation files are in one to one correspondence with the multiplexeddata, and each of the files includes multiplexed data information,stream attribute information, and an entry map.

As illustrated in FIG. 43, the multiplexed data information includes asystem rate, a reproduction start time, and a reproduction end time. Thesystem rate indicates the maximum transfer rate at which a system targetdecoder to be described later transfers the multiplexed data to a PIDfilter. The intervals of the ATSs included in the multiplexed data areset to not higher than a system rate. The reproduction start timeindicates a PTS in a video frame at the head of the multiplexed data. Aninterval of one frame is added to a PTS in a video frame at the end ofthe multiplexed data, and the PTS is set to the reproduction end time.

As shown in FIG. 44, a piece of attribute information is registered inthe stream attribute information, for each PID of each stream includedin the multiplexed data. Each piece of attribute information hasdifferent information depending on whether the corresponding stream is avideo stream, an audio stream, a presentation graphics stream, or aninteractive graphics stream. Each piece of video stream attributeinformation carries information including what kind of compression codecis used for compressing the video stream, and the resolution, aspectratio and frame rate of the pieces of picture data that is included inthe video stream. Each piece of audio stream attribute informationcarries information including what kind of compression codec is used forcompressing the audio stream, how many channels are included in theaudio stream, which language the audio stream supports, and how high thesampling frequency is. The video stream attribute information and theaudio stream attribute information are used for initialization of adecoder before the player plays back the information.

In the present embodiment, the multiplexed data to be used is of astream type included in the PMT. Furthermore, when the multiplexed datais recorded on a recording medium, the video stream attributeinformation included in the multiplexed data information is used. Morespecifically, the moving picture coding method or the moving picturecoding apparatus described in each of embodiments includes a step or aunit for allocating unique information indicating video data generatedby the moving picture coding method or the moving picture codingapparatus in each of embodiments, to the stream type included in the PMTor the video stream attribute information. With the configuration, thevideo data generated by the moving picture coding method or the movingpicture coding apparatus described in each of embodiments can bedistinguished from video data that conforms to another standard.

Furthermore, FIG. 45 illustrates steps of the moving picture decodingmethod according to the present embodiment. In Step exS100, the streamtype included in the PMT or the video stream attribute informationincluded in the multiplexed data information is obtained from themultiplexed data. Next, in Step exS101, it is determined whether or notthe stream type or the video stream attribute information indicates thatthe multiplexed data is generated by the moving picture coding method orthe moving picture coding apparatus in each of embodiments. When it isdetermined that the stream type or the video stream attributeinformation indicates that the multiplexed data is generated by themoving picture coding method or the moving picture coding apparatus ineach of embodiments, in Step exS102, decoding is performed by selectinga reference picture or a motion vector from candidates according to themoving picture decoding method in each of embodiments. Furthermore, whenthe stream type or the video stream attribute information indicatesconformance to the conventional standards, such as MPEG-2, MPEG-4 AVC,and VC-1, in Step exS103, decoding is performed by a moving picturedecoding method in conformity with the conventional standards. Forexample, when the attribute information shows that the stream conformsto the MPEG-4 AVC standard, the stream is decoded on a block-by-blockbasis using a motion vector not selected from the candidates butcalculated from a motion vector of at least one block that is spatiallyor temporally adjacent to a current block.

As such, allocating a new unique value to the stream type or the videostream attribute information enables determination whether or not themoving picture decoding method or the moving picture decoding apparatusthat is described in each of embodiments can perform decoding. Even whenmultiplexed data that conforms to a different standard is input, anappropriate decoding method or apparatus can be selected. Thus, itbecomes possible to decode information without any error. Furthermore,the moving picture coding method or apparatus, or the moving picturedecoding method or apparatus in the present embodiment can be used inthe devices and systems described above.

Sixth Embodiment

Each of the moving picture coding method, the moving picture codingapparatus, the moving picture decoding method, and the moving picturedecoding apparatus in each of embodiments is typically achieved in theform of an integrated circuit or a Large Scale Integrated (LSI) circuit.As an example of the LSI, FIG. 46 illustrates a configuration of the LSIex500 that is made into one chip. The LSI ex500 includes elements ex501,ex502, ex503, ex504, ex505, ex506, ex507, ex508, and ex509 to bedescribed below, and the elements are connected to each other through abus ex510. The power supply circuit unit ex505 is activated by supplyingeach of the elements with power when the power supply circuit unit ex505is turned on.

For example, when coding is performed, the LSI ex500 receives an AVsignal from a microphone ex117, a camera ex113, and others through an AVIO ex509 under control of a control unit ex501 including a CPU ex502, amemory controller ex503, a stream controller ex504, and a drivingfrequency control unit ex512. The received AV signal is temporarilystored in an external memory ex511, such as an SDRAM. Under control ofthe control unit ex501, the stored data is segmented into data portionsaccording to the processing amount and speed to be transmitted to asignal processing unit ex507. Then, the signal processing unit ex507codes an audio signal and/or a video signal. Here, the coding of thevideo signal is the coding described in each of embodiments.Furthermore, the signal processing unit ex507 sometimes multiplexes thecoded audio data and the coded video data, and a stream IO ex506provides the multiplexed data outside. The provided multiplexed data istransmitted to the base station ex107, or written on the recordingmedium ex215. When data sets are multiplexed, the data should betemporarily stored in the buffer ex508 so that the data sets aresynchronized with each other.

Although the memory ex511 is an element outside the LSI ex500, it may beincluded in the LSI ex500. The buffer ex508 is not limited to onebuffer, but may be composed of buffers. Furthermore, the LSI ex500 maybe made into one chip or a plurality of chips.

Furthermore, although the control unit ex501 includes the CPU ex502, thememory controller ex503, the stream controller ex504, the drivingfrequency control unit ex512, the configuration of the control unitex501 is not limited to such. For example, the signal processing unitex507 may further include a CPU. Inclusion of another CPU in the signalprocessing unit ex507 can improve the processing speed. Furthermore, asanother example, the CPU ex502 may serve as or be a part of the signalprocessing unit ex507, and, for example, may include an audio signalprocessing unit. In such a case, the control unit ex501 includes thesignal processing unit ex507 or the CPU ex502 including a part of thesignal processing unit ex507.

The name used here is LSI, but it may also be called IC, system LSI,super LSI, or ultra LSI depending on the degree of integration.

Moreover, ways to achieve integration are not limited to the LSI, and adedicated circuit or a general purpose processor and so forth can alsoachieve the integration. Field Programmable Gate Array (FPGA) that canbe programmed after manufacturing LSIs or a reconfigurable processorthat allows re-configuration of the connection or configuration of anLSI can be used for the same purpose. Such a programmable logic devicecan typically execute the moving picture coding method and/or the movingpicture decoding method according to any of the above embodiments, by,loading or reading from a memory or the like one or more programs thatare included in software or firmware.

In the future, with advancement in semiconductor technology, a brand-newtechnology may replace LSI. The functional blocks can be integratedusing such a technology. The possibility is that the present disclosureis applied to biotechnology.

Seventh Embodiment

When video data generated in the moving picture coding method or by themoving picture coding apparatus described in each of embodiments isdecoded, it is possible for the processing amount to increase comparedto when video data that conforms to a conventional standard, such asMPEG-2, MPEG-4 AVC, and VC-1 is decoded. Thus, the LSI ex500 needs to beset to a driving frequency higher than that of the CPU ex502 to be usedwhen video data in conformity with the conventional standard is decoded.However, when the driving frequency is set higher, there is a problemthat the power consumption increases.

In view of the above, the moving picture decoding apparatus, such as thetelevision ex300 and the LSI ex500 is configured to determine to whichstandard the video data conforms, and switch between the drivingfrequencies according to the determined standard. FIG. 47 illustrates aconfiguration ex800 in the present embodiment. A driving frequencyswitching unit ex803 sets a driving frequency to a higher drivingfrequency when video data is generated by the moving picture codingmethod or the moving picture coding apparatus described in each ofembodiments. Then, the driving frequency switching unit ex803 instructsa decoding processing unit ex801 that executes the moving picturedecoding method described in each of embodiments to decode the videodata. When the video data conforms to the conventional standard, thedriving frequency switching unit ex803 sets a driving frequency to alower driving frequency than that of the video data generated by themoving picture coding method or the moving picture coding apparatusdescribed in each of embodiments. Then, the driving frequency switchingunit ex803 instructs the decoding processing unit ex802 that conforms tothe conventional standard to decode the video data.

More specifically, the driving frequency switching unit ex803 includesthe CPU ex502 and the driving frequency control unit ex512 in FIG. 46.Here, each of the decoding processing unit ex801 that executes themoving picture decoding method described in each of embodiments and thedecoding processing unit ex802 that conforms to the conventionalstandard corresponds to the signal processing unit ex507 in FIG. 46. TheCPU ex502 determines to which standard the video data conforms. Then,the driving frequency control unit ex512 determines a driving frequencybased on a signal from the CPU ex502. Furthermore, the signal processingunit ex507 decodes the video data based on the signal from the CPUex502. For example, it is possible that the identification informationdescribed in Fifth Embodiment is used for identifying the video data.The identification information is not limited to the one described inFifth Embodiment but may be any information as long as the informationindicates to which standard the video data conforms. For example, whenwhich standard video data conforms to can be determined based on anexternal signal for determining that the video data is used for atelevision or a disk, etc., the determination may be made based on suchan external signal. Furthermore, the CPU ex502 selects a drivingfrequency based on, for example, a look-up table in which the standardsof the video data are associated with the driving frequencies as shownin FIG. 49. The driving frequency can be selected by storing the look-uptable in the buffer ex508 and in an internal memory of an LSI, and withreference to the look-up table by the CPU ex502.

FIG. 48 illustrates steps for executing a method in the presentembodiment. First, in Step exS200, the signal processing unit ex507obtains identification information from the multiplexed data. Next, inStep exS201, the CPU ex502 determines whether or not the video data isgenerated by the coding method and the coding apparatus described ineach of embodiments, based on the identification information. When thevideo data is generated by the moving picture coding method and themoving picture coding apparatus described in each of embodiments, inStep exS202, the CPU ex502 transmits a signal for setting the drivingfrequency to a higher driving frequency to the driving frequency controlunit ex512. Then, the driving frequency control unit ex512 sets thedriving frequency to the higher driving frequency. On the other hand,when the identification information indicates that the video dataconforms to the conventional standard, such as MPEG-2, MPEG-4 AVC, andVC-1, in Step exS203, the CPU ex502 transmits a signal for setting thedriving frequency to a lower driving frequency to the driving frequencycontrol unit ex512. Then, the driving frequency control unit ex512 setsthe driving frequency to the lower driving frequency than that in thecase where the video data is generated by the moving picture codingmethod and the moving picture coding apparatus described in each ofembodiment.

Furthermore, along with the switching of the driving frequencies, thepower conservation effect can be improved by changing the voltage to beapplied to the LSI ex500 or an apparatus including the LSI ex500. Forexample, when the driving frequency is set lower, it is possible thatthe voltage to be applied to the LSI ex500 or the apparatus includingthe LSI ex500 is set to a voltage lower than that in the case where thedriving frequency is set higher.

Furthermore, when the processing amount for decoding is larger, thedriving frequency may be set higher, and when the processing amount fordecoding is smaller, the driving frequency may be set lower as themethod for setting the driving frequency. Thus, the setting method isnot limited to the ones described above. For example, when theprocessing amount for decoding video data in conformity with MPEG-4 AVCis larger than the processing amount for decoding video data generatedby the moving picture coding method and the moving picture codingapparatus described in each of embodiments, it is possible that thedriving frequency is set in reverse order to the setting describedabove.

Furthermore, the method for setting the driving frequency is not limitedto the method for setting the driving frequency lower. For example, whenthe identification information indicates that the video data isgenerated by the moving picture coding method and the moving picturecoding apparatus described in each of embodiments, it is possible thatthe voltage to be applied to the LSI ex500 or the apparatus includingthe LSI ex500 is set higher. When the identification informationindicates that the video data conforms to the conventional standard,such as MPEG-2, MPEG-4 AVC, and VC-1, it is possible that the voltage tobe applied to the LSI ex500 or the apparatus including the LSI ex500 isset lower. As another example, it is possible that, when theidentification information indicates that the video data is generated bythe moving picture coding method and the moving picture coding apparatusdescribed in each of embodiments, the driving of the CPU ex502 is notsuspended, and when the identification information indicates that thevideo data conforms to the conventional standard, such as MPEG-2, MPEG-4AVC, and VC-1, the driving of the CPU ex502 is suspended at a given timebecause the CPU ex502 has extra processing capacity. It is possiblethat, even when the identification information indicates that the videodata is generated by the moving picture coding method and the movingpicture coding apparatus described in each of embodiments, in the casewhere the CPU ex502 has extra processing capacity, the driving of theCPU ex502 is suspended at a given time. In such a case, it is possiblethat the suspending time is set shorter than that in the case where whenthe identification information indicates that the video data conforms tothe conventional standard, such as MPEG-2, MPEG-4 AVC, and VC-1.

Accordingly, the power conservation effect can be improved by switchingbetween the driving frequencies in accordance with the standard to whichthe video data conforms. Furthermore, when the LSI ex500 or theapparatus including the LSI ex500 is driven using a battery, the batterylife can be extended with the power conservation effect.

Eighth Embodiment

There are cases where a plurality of video data that conforms todifferent standards, is provided to the devices and systems, such as atelevision and a cellular phone. In order to enable decoding theplurality of video data that conforms to the different standards, thesignal processing unit ex507 of the LSI ex500 needs to conform to thedifferent standards. However, the problems of increase in the scale ofthe circuit of the LSI ex500 and increase in the cost arise with theindividual use of the signal processing units ex507 that conform to therespective standards.

In view of the above, what is conceived is a configuration in which thedecoding processing unit for implementing the moving picture decodingmethod described in each of embodiments and the decoding processing unitthat conforms to the conventional standard, such as MPEG-2, MPEG-4 AVC,and VC-1 are partly shared. Ex900 in FIG. 50A shows an example of theconfiguration. For example, the moving picture decoding method describedin each of embodiments and the moving picture decoding method thatconforms to MPEG-4 AVC have, partly in common, the details ofprocessing, such as entropy coding, inverse quantization, deblockingfiltering, and motion compensated prediction. It is possible for adecoding processing unit ex902 that conforms to MPEG-4 AVC to be sharedby common processing operations, and for a dedicated decoding processingunit ex901 to be used for processing which is unique to an aspect of thepresent disclosure and does not conform to MPEG-4 AVC. In particular,since the aspect of the present disclosure is characterized by inversequantization, it is possible, for example, for the dedicated decodingprocessing unit ex901 to be used for inverse quantization, and for thedecoding processing unit to be shared by any or all of the otherprocessing, such as entropy decoding, deblocking filtering, and motioncompensation. The decoding processing unit for implementing the movingpicture decoding method described in each of embodiments may be sharedfor the processing to be shared, and a dedicated decoding processingunit may be used for processing unique to that of MPEG-4 AVC.

Furthermore, ex1000 in FIG. 50B shows another example in that processingis partly shared. This example uses a configuration including adedicated decoding processing unit ex1001 that supports the processingunique to an aspect of the present disclosure, a dedicated decodingprocessing unit ex1002 that supports the processing unique to anotherconventional standard, and a decoding processing unit ex1003 thatsupports processing to be shared between the moving picture decodingmethod according to the aspect of the present disclosure and theconventional moving picture decoding method. Here, the dedicateddecoding processing units ex1001 and ex1002 are not necessarilyspecialized for the processing according to the aspect of the presentdisclosure and the processing of the conventional standard,respectively, and may be the ones capable of implementing generalprocessing. Furthermore, the configuration of the present embodiment canbe implemented by the LSI ex500.

As such, reducing the scale of the circuit of an LSI and reducing thecost are possible by sharing the decoding processing unit for theprocessing to be shared between the moving picture decoding methodaccording to the aspect of the present disclosure and the moving picturedecoding method in conformity with the conventional standard.

The herein disclosed subject matter is to be considered descriptive andillustrative only, and the appended Claims are of a scope intended tocover and encompass not only the particular embodiment(s) disclosed, butalso equivalent structures, methods, and/or uses.

INDUSTRIAL APPLICABILITY

The present disclosure is applicable to an image encoding apparatus, animage decoding apparatus, and the like.

The invention claimed is:
 1. A video decoding method for decoding abitstream corresponding to a current picture in a video using one ormore reference pictures, the video decoding method comprising: obtaininga classification of a picture in the video; judging whether or not thepicture is a key picture having a predetermined frame type; selecting,when the classification of the current picture is a predeterminedclassification indicating a picture usable as a switching point, one ormore valid reference pictures from among all valid reference picturesfor the current picture in a reference picture memory, each of the validreference pictures for the current picture being the key picture;constructing a reference picture list including at least one of the oneor more valid reference pictures; and decoding the current picture byperforming motion prediction on the current picture using the validreference pictures included in the reference picture list, wherein inthe judging, the picture is judged to be the key picture when a frametype parameter of the picture is zero, and wherein, in the selecting,when the classification of the current picture is the predeterminedclassification and when the frame type parameter of the current pictureis greater than zero, only the one or more valid reference pictures areselected, each of the one or more valid reference pictures being the keypicture.
 2. The video decoding method according to claim 1, furthercomprising obtaining classification information indicating theclassification of the current picture, from a header of the bitstream.3. The video decoding method according to claim 2, further comprisingobtaining a temporal level parameter indicating a temporal level of thecurrent picture, from the header of the bitstream.
 4. The video decodingmethod according to claim 2, further comprising obtaining selectioninformation and reference information from a header of the bitstream,the selection information indicating whether or not the temporallyscalable scheme is to be used for decoding the video, and the referenceinformation indicating the reference pictures in the reference picturememory.
 5. The video decoding method according to claim 1, wherein thekey picture is an inter-predicted picture.
 6. The video decoding methodaccording to claim 1, wherein, in the selecting of the one or more validreference pictures, when the classification of the current picture isnot the predetermined classification, a non-key picture is selected asone of the one or more valid reference picture.
 7. The video decodingmethod according to claim 1, wherein, in the selecting of the one ormore valid pictures, when the classification of the current picture isnot the predetermined classification, the all reference pictures in thereference picture memory are selected as the one or more valid referencepictures, the constructing further includes: constructing a firstreference picture list including one or more reference pictures in thereference picture memory, using a temporal distance between each of theone or more reference pictures and the current picture; constructing asecond reference picture list including the one or more valid referencepicture, using the temporal distance between the each of the one or morereference pictures and the current picture and the classification of theeach of the one or more reference pictures; and reordering the firstreference picture list to make the first reference picture list beequivalent to the second reference picture list, and in the decoding,the current picture is predicted, using the reordered first referencepicture list.
 8. The video decoding method according to claim 1, furthercomprising: selecting a first reference picture group including one ormore key pictures out of the reference picture memory; identifying, whenthe classification of the current picture is not the predeterminedclassification, (i) a first boundary picture as a key picture having anearest temporal instance to the current picture among key picturesdisplayed earlier than the current picture, and (ii) a second boundarypicture as a key picture having a nearest temporal instance to thecurrent picture among key pictures displayed later than the currentpicture; performing, when the second boundary picture is not present,(i) selection of a second reference picture group including anon-key-reference picture displayed later than the first boundarypicture, and (ii) addition of the second reference picture group to thefirst reference picture group; performing, when the second boundarypicture is present, (i) selection of a third reference picture groupincluding a non-key-reference picture displayed later than the firstboundary picture and earlier than the second boundary picture, and (ii)addition of the third reference picture group to the first referencepicture group; and placing the first reference picture group on thereference picture list which is sorted according to a predeterminedscheme, using a temporal distance to the current picture and theclassification.
 9. A video decoding apparatus which decodes a bitstreamcorresponding to a current picture in a video using one or morereference pictures, the video decoding apparatus comprising: anobtainment unit configured to obtain a classification of a picture inthe video; a judgment unit configured to judge whether or not thepicture is a key picture type having a predetermined frame type; a validreference picture selection unit configured to select, when theclassification of the current picture is a predetermined classificationindicating a picture usable as a switching point, one or more validreference pictures from among all valid reference pictures for thecurrent picture in a reference picture memory, each of the validreference pictures for the current picture being the key picture type; areference picture list construction unit configured to construct areference picture list including at least one of the one or more validreference pictures; and a decoding unit configured to decode the currentpicture by performing motion prediction on the current picture using theone or more valid reference pictures included in the reference picturelist, wherein in the judging, the picture is judged to be the keypicture type when a frame type parameter of the picture is zero, andwherein, in the selecting, when the classification of the currentpicture is the predetermined classification and when the frame typeparameter of the current picture is greater than zero, only the one ormore valid reference pictures are selected, each of the one or morevalid reference pictures being the key picture type.
 10. A videodecoding method for decoding a bitstream corresponding to a currentpicture in a video using one or more reference pictures, the videodecoding method comprising: obtaining a classification of a currentpicture in the video; judging whether or not a frame type parameter ofthe current picture greater than zero; when the classification of thecurrent picture is a predetermined classification indicating a pictureusable as a switching point and when the frame type parameter of thecurrent picture is greater than zero, selecting only one or morereference picture from among all valid reference pictures for thecurrent picture in a reference picture memory, the frame type parameterfor each of the valid reference pictures being zero; constructing areference picture list including at least one of the selected one ormore reference pictures; and decoding the current picture by performingmotion prediction on the current picture using the reference picturelist.
 11. A video decoding apparatus that decodes a bitstreamcorresponding to a current picture in a video using one or morereference pictures, the video decoding apparatus comprising: anobtainment unit configured to obtain a classification of a currentpicture in the video; a judgment unit configured to judge whether or nota frame type parameter of the current picture greater than zero; a validreference picture selection unit configured to select, when theclassification of the current picture is a predetermined classificationindicating a picture usable as a switching point and when the frame typeparameter of the current picture is greater than zero, only one or morereference picture from among all valid reference pictures for thecurrent picture in a reference picture memory, the frame type parameterfor each of the valid reference pictures being zero; a reference picturelist construction unit configured to construct a reference picture listincluding at least one of the selected one or more reference pictures;and a decoding unit configured to decode the current picture byperforming motion prediction on the current picture using the referencepicture list.